Authority: Community discussion
Official ruling confirmed: unknown
Source: Reddit: r/Yugioh101
Link: www.reddit.com/r/Yugioh101/comments/1wjef2v/once_per_turn_effect/
Format: TCG
Status: resolved
Date: 18 September 2026

1. Question

A player asked on Reddit about using a monster’s once-per-turn effect after taking control of it from the opponent.

In the first scenario, the opponent Special Summons Tearlaments Merrli and activates its effect to mill cards. Merrli is then sent to the GY. The player subsequently uses Dharc the Dark Charmer, Gloomy to Special Summon Merrli to their own field.

The question is whether Merrli’s mill effect can be activated again after it has changed control.

The player also asked about a similar situation involving Decode Talker Heatsoul: if the opponent controls Heatsoul and has already activated its once-per-turn effect, can the player activate that effect again after taking control of Heatsoul?

2. Reddit Discussion

A commenter identified as having a YGOrganization badge answered that the effect can be used again.

For the Merrli scenario, the answer was that each player can use the effect once per turn. Since the effect had previously been used by the opponent, taking control of Merrli allows the new controller to use the effect.

The original poster then asked whether the same principle applies to Heatsoul when taking control of it after the opponent has already used its effect.

The same commenter again answered yes.

3. Summary of the Reddit Answer

Scenario	Reddit Answer
Opponent uses Merrli’s effect, then you take control of Merrli	You can use the effect
Opponent uses Heatsoul’s effect, then you take control of Heatsoul	You can use the effect
A once-per-turn effect used by one player prevents another player from using it after taking control	No, according to the Reddit answer

The central point of the Reddit response is that the once-per-turn restriction applies per player in these scenarios. The previous controller having used the effect does not prevent the new controller from using it.

4. Conclusion

According to the Reddit discussion, yes, you can activate the relevant once-per-turn effect after taking control of the monster if the previous controller was the player who had already used that effect that turn.

The discussion gives this answer for both the Tearlaments Merrli and Decode Talker Heatsoul scenarios.

This post documents the answer given in the Reddit discussion. The source itself does not provide an official Konami ruling or policy document establishing the interaction, so the Reddit answer should not be presented as an official Konami ruling.