Siege, The Traitorous

Double Strike, Shroud, Trample
Dethrone (Whenever this creature attacks the player
with the most life or tied for the most life, put a +1/+1 counter on it.)
At the beginning of your end step, if you don't
have the highest life total. Target player gains
control of Siege, The Traitorous.
"Spoils to victor."