Riptide Chimera

The upkeep trigger reads like a drawback until you stack a deck around it, at which point it becomes the engine. A 3/4 flyer for three mana is already a reasonable rate; the price of that rate is that you must return an enchantment you control to your hand every upkeep, and the design assumes you will want to. This is the constellation enabler dressed as a creature: anything that triggers when an enchantment enters or leaves the battlefield gets a free activation each turn from a card that already pays for itself as a body. Cheap auras, enters-the-battlefield enchantments, and the constellation triggers prevalent in its enchantment-heavy era all turn the mandatory bounce from tax into payoff, replaying value the way a sacrifice outlet recycles its fuel. The trigger is non-optional: you return one enchantment every upkeep whether or not you have a good target, which is the friction the rate is paying for, and the reason it wants a board you have built rather than one you merely have. The trap is the empty board. Because the Chimera is itself an enchantment, with nothing else in play it has no choice but to bounce itself before it can ever swing, forcing you to recast it for three each turn just to keep a blocker on the table. The card is only an engine when it has fuel; without one, it is a creature that refuses to stay down.