You gain control of the targeted monster in the same Battle Position that it was in on your opponent's side of the field. If it is face-down, you may Flip Summon it and any Flip Effect it has is activated. During your End Phase, it is returned to your opponent's side of the field in the same Battle Position as you last had it in. So if you attacked with the monster and it remained in Attack Position, it will return to your opponent in Attack Position.

You can use the monster you control through the effect of "Change of Heart" as a Tribute for a Tribute Summon or Tribute Set, or for an effect like "Cannon Soldier's".

Ameba: If your opponent uses "Change of Heart" on a face-down "Ameba" and Flip Summons it, when it returns to you during the End Phase, its effect activates and you take 2000 damage.

Charmer: If you take control of the opponent’s monster with a “Charmer” and the opponent takes control back with “Change of Heart”, control still reverts to you after the effect of “Change of Heart” expires (even though it wasn’t your monster originally).

Bazoo the Soul-Eater:" If you remove Monster Cards from your Graveyard to increase the ATK of "Bazoo the Soul-Eater", then on your opponent's turn he uses "Change of Heart" to gain control of the same "Bazoo the Soul-Eater", your opponent can remove cards from his Graveyard to further increase the ATK. The ATK increase you caused will end during that End Phase, and the ATK increase your opponent caused will end during your End Phase.

Big Bang Shot:" The effect of "Big Bang Shot" that removes the equipped monster from play can be resolved between steps of a chain. For example, if "Change of Heart" targets a monster equipped with "Big Bang Shot", and "Mystical Space Typhoon" is chained to "Change of Heart" to destroy "Big Bang Shot", first resolve "Mystical Space Typhoon" and destroy "Big Bang Shot", then remove the monster that was equipped from play, and THEN resolve "Change of Heart" (and the effect of "Change of Heart" disappears).

Blindly Loyal Goblin:" If your opponent takes control of your "Blindly Loyal Goblin" with "Change of Heart" and flips it face-up, control of the monster does not return to you.

Blindly Loyal Goblin:" Your opponent cannot use "Change of Heart"on your face-up "Blindly Loyal Goblin".

Blindly Loyal Goblin:" If your opponent tries to use "Change of Heart" on your face-down "Blindly Loyal Goblin", and you chain "Ceasefire" to flip it face-up, the effect of "Change of Heart" is negated.

Cobra Jar:" When the "Poisonous Snake Token" is destroyed as a result of battle, it is the opponent of "Cobra Jar"s controller that takes the damage; so even if the opponent had taken control of the "Poisonous Snake Token" with "Change of Heart", he/she still takes the damage when it is destroyed.

Creature Swap:" A player may activate "Change of Heart" to gain control of an opponent's monster, and then activate "Creature Swap" and select that monster to return to the opponent. At the end of the turn, the monster targeted by "Change of Heart" does not switch sides again since it is already on the owner's side of the field.

Deck Devastation Virus:" If you use "Change of Heart" to take control of your opponent's "Magicial Scientist" during the turns after "Deck Devastation Virus" has resolved, it will not be destroyed. If you then use its effect to Special Summon "Thousand-Eyes Restrict", it will also not be destroyed.

Deepsea Warrior:" If you take control of your opponent's face-down "Deepsea Warrior" with "Change of Heart" while "Umi" is face-up on the field, when it is flipped face-up it is immediately returned to your opponent.

Desrook Archfiend:" When you control your opponent's "Terrorking Archfiend" with "Change of Heart", and it is destroyed, you can activate "Desrook Archfiend" from your hand to Special Summon the "Terrorking Archfiend" back to your side of the field.

Different Dimension Gate:" When your opponent's monster on your side of the field that you control with "Change of Heart"is removed with "Different Dimension Gate", it returns to your side of the field when "Different Dimension Gate" is destroyed, and then immediately returns to your opponent's side of the field.

Dramatic Rescue:" You can activate "Dramatic Rescue" when an Amazoness on your side of the field is targeted, such as"Change of Heart"

Ectoplasmer:" If you Tribute your opponent's monster that you controlled with"Change of Heart", your opponent takes the damage even though it was their monster.

Fatal Abacus:" It is the owner of the Monster Card that takes the damage, so if you control your opponent's monster through the effect of "Change of Heart" and Tribute it, your opponent takes the 500 points of damage.

Freed the Matchless General:" If your opponent activates "Change of Heart" and gains control of this card while it is face-down, and it is then flipped face-up, they retain control of it until the end of the turn. This is because the effect of "Freed the Matchless General" must be applied when the Spell Card is activated.

Griggle:" If your opponent uses "Change of Heart" on a face-down "Griggle" and Flip Summons it, when it returns to you during the End Phase, its effect activates and your opponent will gain 3000 Life Points.

Harpie Lady 3:" If you control "Harpie Lady 3" and "Gemini Elf" and your opponent activates "Change of Heart" to gain control of "Gemini Elf", then attacks your "Harpie Lady 3", your "Gemini Elf" cannot attack for 2 of your opponent's turns, even after it returns to your side of the field.

Insect Princess:" When you have "Insect Princess" and a Defense Position "Crass Clown" on your side of the field, and "DNA Surgery" is making "Crass Clown" an Insect-Type, and your opponent takes control of "Crass Clown" with "Change of Heart", "Crass Clown" is changed to Attack Position because of "Insect Princess" effect and its effect activates.

Interdimensional Matter Transporter:" If you control your opponent's monster because of "Change of Heart"and remove the monster with "Interdimensional Matter Transporter", the monster returns to your side of the field, then immediately returns to your opponent's side of the field.

Kaiser Colosseum:" Your opponent cannot use "Monster Reborn", "Scapegoat", etc. while "Kaiser Colosseum" prevents him from placing new monsters. However, your opponent CAN use "Change of Heart"

Kaiser Colosseum:" If the player who controls "Kaiser Colosseum" has his only monster taken by the opponent with "Change of Heart", then the opponent can place more monsters because "Kaiser Colosseum"s effect is no longer active until the player has at least 1 monster again.

Last Turn:" "Last Turn" is a very special Trap Card with very special and unusual rules. The most important thing to understand about "Last Turn" is that not all of its effects are applied when the Trap Card resolves. When "Last Turn" (the Trap Card itself) resolves, the activating player selects 1 monster on their side of the field, and all other cards on the field and in both players' hands are sent to the Graveyard. That is all that happens when "Last Turn" resolves. After that, the turn player Special Summons 1 monster from their Deck. After that, a special Battle Phase occurs. Then, during the End Phase, the victory check of "Last Turn" is applied. "Last Turn" sets up several effects that resolve later in the turn long after the Trap Card itself has resolved. Several other cards do this too, like "Last Will" and "Change of Heart".

Last Turn:" "Last Turn" as a chain to "Change of Heart": Suppose the turn player activates "Change of Heart" and the opponent chains "Last Turn", then the opponent selects the monster targeted by "Change of Heart" for "Last Turn" (since it's still on his side of the field, as "Change of Heart" hasn't resolved yet). Then "Change of Heart" resolves and the turn player gains control of the monster, then Special Summons for "Last Turn". There is no special Battle Phase. Assuming that the opponent somehow survives the standard Battle Phase, during the End Phase, the turn player has priority to activate and resolve an effect. If the turn player activates and resolves "Change of Heart", then the monster goes back to the opponent and (assuming nothing else has happened), both players each have 1 monster and the result is a DRAW. If the turn player passes priority to the opponent, the opponent can activate and resolve the effect of "Last Turn" before "Change of Heart", and in this case the turn player still has 2 monsters and the opponent has zero, so the turn player would win. If the turn player passed priority to the opponent and the opponent passes it back, the turn player MUST activate and resolve an effect, so the effect of "Change of Heart" would expire and both players would have 1 monster each, resulting in a DRAW.

Lost Guardian:" Example: Player A controls 2 monsters. Player B activates "Change of Heart" to take control of one of them, then activates "Different Dimension Gate" to remove both from play. Both monsters are in Player A's "removed zone" while removed from play (so Player A's "Lost Guardian" would have 1400 DEF). When "Different Dimension Gate" is destroyed, the monster Player B took control of will return to Player B's side of the field (if possible, if not it is destroyed) before returning to Player A's side of the field.

Mataza the Zapper:" You cannot use "Change of Heart" on a face-up "Mataza the Zapper".

Mirage Dragon:" The effect of this monster makes the opponent of this monster's current controller unable to activate Trap Cards during the Battle Phase. If you take control of your opponent's monster with "Change of Heart" during your turn, your opponent cannot activate Trap Cards during your Battle Phase, but you can.

Pitch-Black Warwolf:" The effect of this monster makes the opponent of this monster's current controller unable to activate Trap Cards during the Battle Phase. If you take control of your opponent's monster with "Change of Heart" during your turn, your opponent cannot activate Trap Cards during your Battle Phase, but you can.

Precious Cards from Beyond:" If you Tribute Summon or Set with 2 monsters, and 1 of them was your opponent's monster that you used with "Change of Heart"you can activate "Precious Cards from Beyond".

Remove Brainwashing:" If "Remove Brainwashing" is destroyed, control does not revert again, so if I activate "Change of Heart" and my opponent chains "Remove Brainwashing", control of the monster comes to me and then reverts to my opponent. Then, later in the turn, if "Remove Brainwashing" is destroyed with "Heavy Storm", control does not revert back to me and remains with the original owner. (The same for "Creature Swap", etc.)

Revival Jam:" If you activate "Change of Heart" to take control of "Revival Jam", and it is sent to the Graveyard as a result of battle, the owner (not you) gets the option to pay 1000 Life Points to Special Summon "Revival Jam" to their side of the field.

Rivalry of Warlords:" If "Rivalry of Warlords" is active and you take control of your opponent's face-up monster with "Change of Heartdestroyed.Monsters sent to the Graveyard by "Rivalry of Warlords" due to their Type are not destroyed.

Scapegoat:" If you control 2 monsters and your opponent activates "Change of Heart" to gain control of one and you later activate "Scapegoat" your monster will be destroyed during the End Phase if all 5 of your Monster Card Zones are still occupied.

Skull Knight 2:" If you activate "Change of Heart" to control your opponent's "Skull Knight #2" and Tribute it to Tribute Summon a Fiend-Type monster you can Special Summon a "Skull Knight #2" from your Deck. But if you activate "Soul Exchange" to Tribute a "Skull Knight #2" on your opponent's side of the field, neither player can activate its effect.

Spatial Collapse:" When you have 4 cards on your side of the field while "Spatial Collapse" is active, you cannot activate "Change of Heart".

Spellbinding Circle:" You can activate "Change of Heart" and take control of a monster targeted by "Spellbinding Circle" but you cannot attack with it or change its Battle Position.

Spirit Reaper:" "Spirit Reaper" is only destroyed by its own effect if it is face-up on the field when the effect designating it as a target activates, AND after the effect designating it as a target resolves If a face-down "Spirit Reaper" is targeted with "Change of Heart", then Flip Summoned, it is not destroyed because it was face-down when "Change of Heart" was activated. If "Spirit Reaper" is targeted by the effect of "Relinquished", "Spirit Reaper" is an Equip Spell Card after the effect of "Relinquished" resolves, so it is not destroyed

Spirit Reaper:" You cannot activate"Change of Heart" and target "Spirit Reaper" if you do not have an empty Monster Card Zone.

The Legendary Fisherman:" If you take control of your opponent's face-down "The Legendary Fisherman" with "Change of Heart" while "Umi" is face-up on the field, when it is flipped face-up it is immediately returned to your opponent.

The Secret of the Bandit:" This card's effect targets a monster, so you select the target at the activation of the card. You may select a monster on the opponent's side of the field. If you target an opponent's monster, and then take control of it with "Change of Heart" and attack and do Battle Damage to your opponent, they will discard a card. If you target an opponent's monster, and attack that monster with a weaker monster, causing Battle Damage to yourself, no one will discard a card. The monster targeted by your "The Secret of the Bandit" must deal Battle Damage to the opponent's Life Points for the effect to activate.

Winged Kuriboh:" Because the effect of "Winged Kuriboh" activates in the Graveyard, it is the original owner that will get the effect. So if the opponent took control with "Change of Heart"if it is destroyed then it goes to the original owner's Graveyard and they get the effect.

Zolga:" When your opponent takes your "Zolga" with "Change of Heart" and Tribute Summons with it, your opponent (the controller of "Zolga" when it was Tributed) increases his Life Points.