The Tarnished

Runes Into Strength - At the beginning of each
end step, place X +1/+1 counters on The
Tarnished, where X is the number of creatures
that died this turn.
Arise Now, Ye Tarnished - If the Tarnished
would leave the battlefield, remove half of the
+1/+1 counters on it instead, rounded down.
"Cross the fog, to the Lands Between, to stand before
the Elden Ring. And become the Elden Lord."