There's a lot of staples for Counters decks here, like Inspiring Call, Inexorable Tide, Hardened Scales, and it's the first time we've seen Damning Verdict reprinted, one of the best cards for a Counters deck as a one-sided wipe and it was quite expensive for that reason
But instead of only being a one-off effect like Mickey, Belle lets you just do it every single turn
If the copied creature had in its mana cost, X is 0
Now winning through combat damage gives way to combo kills the further up the brackets you go, but I can see Cloud decks rocking well in Core and Modified Brackets
So this effect doesn't feel helpful, it feels like it hurts you more than anything
This is a list of all the instant-speed tricks in Final Fantasy