Spell counters are a type of counter that is placed on permanents, typically creatures, to modify their abilities or characteristics. They are typically added or removed by spells or abilities.
Turn Structure
In Magic: The Gathering, players take turns, and each turn is divided into phases.
* Your Turn: You are the active player and can perform actions like casting spells, activating abilities, and attacking.
* Opponent's Turn: Your opponent is the active player, and they can perform actions like casting spells, activating abilities, and attacking.
Rules of Play
The rules of Magic: The Gathering dictate that you can only use spells, abilities, and effects that are specifically allowed during your turn.
Conclusion
Therefore, since spell counters are usually added or removed by spells or abilities, and you cannot use spells or abilities on your opponent's turn, you cannot use spell counters on your opponent's turn.
Note: There are some exceptions to this rule, such as abilities that trigger on your opponent's turn, but these abilities are specifically worded to allow for use on your opponent's turn.