Sure, playing a 5-mana enchantment that basically says, you win the game sounds super powerful, but since youll be putting over 200 cards in your deck, the odds of you drawing it will be pretty low
You only have to pay energy after they block, and unless they have tokens to feed you, theres some inherent risk in blocking
If you destroy some of your own permanents with Convert to Slime, they'll go to your graveyard in time for their types to be counted for the delirium ability
(Whenever a creature with myriad attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control
Happy Holidays from MTG Insider
For fun, one of them, the white one named Goldmeadow Lookout, made a creature token called a Goldmeadow Harrier that didn't yet exist in Magic