The Thinner

At the beginning of each upkeep, if there is exactly one untapped creature, exile it and put a +1/+1 counter on The Thinner.
At the Beginning of each end step, if there is exactly one tapped creature, exile it and put a +1/+1 counter on The Thinner.
{1}{u}, Remove 2 +1/+1 counters from the Thinner: Tap or untap The Thinner.