Loba, The High-Born Thief

At the beginning of each player's upkeep, that
player may create a treasure token.
{1}{t} Gain control of up to one treasure token
a target opponent controls. If they control no
treasure tokens, instead gain control of
target artifact they control.
Whenever you gain control of an opponent's artifact, Loba, The High-Born Thief gains a
+1/+1 counter.