Escalate appears on Instants and Sorceries. Specifically, modal instants and sorceries, where you have a choice of several possible effects when you cast the spell. When you cast a spell with the mechanic, you chose a mode for its normal cost. You could then choose additional modes by paying the Escalate cost, adding another effect each time you paid that cost. You couldn’t choose the same mode twice, so you couldn’t just endlessly copy an effect if you had infinite mana. And choosing to Escalate or not happened as you cast the spell as a whole, so no weird timing tricks or anything.
Escalate was based off the Entwine mechanic, and generally featured on cards with several smaller effects as opposed to huge game-breaking ones. Several card with the mechanic did break through into constructed tournament play, as modal spells are always nice to have, especially when there’s an option for simply getting all the modes at once. Escalate could certainly see a return some day, although there is a bit of a limit to what effects cards with it can have before it starts getting a little too powerful.
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