Sarakhan, Unending Form

Indestructible, flying, worthy (This creature
can't be blocked by creatures with -1/-1 counters
on them)
When Sarakhan, Unending Form enters the battlefield, all creatures gain changeling until
end of turn. (All creatures have all creature types.)
Sarakhan, Unending Form's power and
toughness are equal to the number of creatures
on the battlefield.