darn 6k gems f2p how long has he been grinding "_"
I believe when you built your core team, you won't need event hero to clear the quests. So it becomes an option like, "do I want to keep as collection?" or "for future advancement"?
For most F2P players like me, I want event heros to clear as high as possible for the highest rewards and event points. Like now, without miu, I pretty much stuck and it also mean that I will lose out in the event ladder when it comes.
But if i got a core team, (that have actually cleared legend with ease) there shouldn't be much difficutly to maintain a level in the ladder.