Dismiss into Dream
The trick is what it does to your own removal. Once this resolves, every creature your opponents control inherits a clause that turns any targeting into a death sentence: not just your spells, but their own pump effects, their own protection auras, any ability that has to point at a creature to function. A single Shock becomes hard removal for anything, a tap effect kills, even an opponent's own targeted blessing becomes an own-goal. The Illusion type-grafting is the mechanism, recasting the entire opposing board as the fragile creature class that has always punished interaction, and the sacrifice trigger does the rest: no damage to calculate, no toughness to clear, no indestructible to route around, since sacrifice sidesteps the lot. Seven mana for an enchantment that kills nothing on its own is a deliberate tax, not an oversight: you are paying for a board state you have to build around afterward, holding cheap targeted effects and a board you can profitably trade into. This is a card that rewrites the rules of engagement rather than affecting it directly, leaving the actual killing to whatever pinprick of a spell you have left in hand. That gap between the splashy global rewrite and the cheap follow-up that exploits it is exactly the texture this kind of enchantment lives or dies on.
