Game Mode: GMace (Ghost Minion Ace)

When you die, you spawn as a minion, until all teammates are dead. Then everyone respawns normally. The minion you get to play as would be based on a modified ward item, I guess. It can be upgraded to other ward items as normally. if you don't have the item, you can't spawn as a minion. If you die as a minion, you keep resawning as a minion. There is no death timer for minions, and once the other team gets an Ace, all five champions instantly respawn.

Maybe grant a free respawn if all teammates are at base, too.

Twisted Treeline?