Here is my idea on how to balance Lemon:
•) change Fairy’s Dust: make it so that puts to sleep all allies on entrance for 200 seconds.
•) change Fairy’s Hymn: make it put all enemies asleep with a 100% chance but keep the original restriction (2 allies must be asleep). Also, it can’t be used if before 250 seconds after the start of the match (to avoid OoO Jackalhotep abuse).
That way:
•) you can still put all enemies asleep, just with a bit more effort
•) no more guaranteed value on entrance, gives the enemy a chance to fight back without SPECIFICALLY building a counter to it that would be mostly ineffective against basically any other strategy
•) still has Potent Sleep to keep the sleep lock going and Slayerbane All in case the sleeplock doesn’t start.
Still sounds OP, to me, just more balanced.