There are a lot of triggered abilities in magic. Most seasoned players can recognize them, and they’re often some of the most common abilities in the game, probably followed by replacement effects and then activated abilities. Still, people can misunderstand what is and isn’t a triggered ability. Enter Strionic Resonator and that amazing reminder text. When, Whenever, and at are words used in every variation of triggered ability, and this card helps you copy them. ETB triggers, Cast triggers, any sort of thing can be copied and doubled. I’ve seen this used to gross powers such as copying Brago’s blink trigger, or even just reusing a Eternal Witness trigger for only two mana more. It depends on the deck you put this in how powerful it can be, from infinite combo to just good synergy. I don’t expect triggered abilities to be copied again anytime soon, unless the next commander set has something to say about it.