Whenever a creature you control
diesIs put into a graveyard from the battlefield. (CR 700.4), each opponent chooses a creature they control and exiles it.
At the beginning of your end step, if a player controls no creatures,
sacrificeTo sacrifice a permanent, its controller moves it from the battlefield directly to its owner’s graveyard. A player can’t sacrifice something that isn’t a permanent, or something that’s a permanent they don’t control. Sacrificing a permanent doesn’t destroy it, so regeneration or other effects that replace destruction can’t affect this action. (CR 701.21) Sothera, then put a creature card exiled with it onto the battlefield under your control with two additional +1/+1
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on it.