Gandalf, the Grey

When Gandalf, the Grey enters the battlefield,
create Shadowfax, a legendary 0/0 white Horse
creature token with haste. Put X +1/+1 counters
on it, where X is the number of creatures in your
fellowship. (Your fellowship consists of up to one
each of Dwarf, Elf, Hobbit and Human.)
When Gandalf, the Grey leaves the battlefield,
create Gandalf, the White, a legendary 3/4 white
Human Wizard creature token.