Twinned Spell is a two-mana spell that allows two players to cast the same spell at the same time. Does this mean that Twinned Spell takes up two spell slots in a player’s deck?
The answer to this question is a little complicated. Twinned Spell technically does not take up any spell slots; rather, it allows two players to cast the same spell simultaneously. Because of this, Twinned Spell can be used in any deck that has the necessary cards to cast it. However, because Twinned Spell functions as a single spell, it is often more powerful than two individual spells would be.
This means that Twinned Spell can be useful in decks that rely on synergies or card combinations to be effective. Because of its flexibility, Twinned Spell can be used in almost any deck type.