Havoc Festival

A symmetrical doomsday clock with no off switch. The upkeep trigger is what gives it teeth: halving life and rounding up means a player at 20 drops to 10, then 5 (losing 3), then 2, then 1, and from 1 the next halving rounds 0.5 up to a full point of loss, finishing the job. The descent is not gentle and it does not stall short of zero; once a player is low enough, "half, rounded up" simply equals their remaining life and the game ends on the math alone. The life-gain lock is the load-bearing clause, not the flashy one: without it, this is a race anyone with a Sanguine Bond shell or a lifelink creature can simply outrun. With it, the only counterplay is killing the enchantment or killing the opponent first. That makes it a card for the player who wants to convert a board-state advantage into a guaranteed close, or who has already decided the game should end in flames regardless of who is ahead. It rewards being the aggressor and punishes durdling on both sides of the table equally, which is the honest contract of a symmetrical effect: you have to be set up to win the race you just started for everyone.