Welcome back to the Rules Tips Blog! Today we’ll be covering a specific kind of triggered ability: The kind that let you pay for value! For example, there’s a cycle of common creatures in Aether Revolt, all of which have “Thriving” in their name- Thriving Ibex, Thriving Turtle, Thriving Rats, Thriving Grubs, and Thriving Rhino. They give you EE when they enter the battlefield, and each time they attack you can pay EE to give them a +1/+1 counter; they bring enough energy to boost themselves once, but if you’ve got access to energy from somewhere else, you can keep on growing these things every time they attack. But what happens if you have 6 or 8 energy at the ready when you attack with one? Can you go all-in with that and boost it up big?
You cannot! Unlike activated abilities, which you can activate as many times as you can pay for, these triggers only let you pay once. As the trigger resolves, either you pay EE, or you don’t; it’s a binary choice. You can’t pay EEEE to get two counters, or EEEEEE for three counters- it’s EE for 1 counter, or nothing. The same is true of other triggers that let you pay some cost as they resolve (for example, Lifesmith from Scars of Mirrodin). You can pay the cost they allow for the effect they allow, or you can choose not to. You can’t pour 10 mana into a Lifesmith trigger to gain 30 life. Of course, if you can get the trigger to fire multiple times, you can pay for multiple triggers; if you activated Aggravated Assault you could attack with your Thriving Grubs, pay EE to boost them, then pop Assault to untap them and swing again, paying another EE to boost them. Just remember that you need to trigger it more than once to PAY for it more than once!
Today’s Rules Tip was written by Trevor Nunez