Thi'ing, the Indecisive

Indecision: Whenever another creature enters the battlefield, you may have Thi'ing, the Indecisive
become a copy of that creature, except its name is
Thi'ing, the Indecisive and it has this ability. If you
do, put an identity counter on Thi'ing.

Remove an identity counter from Thi'ing: target Shapeshifter you control becomes a copy of Thi'ing, except it keeps its name and it doesn't have
Indecision.