Shadowfax

Indestructible, Haste
At the beginning of your end step put a +1/+1
counter on Shadowfax.
"I do not ride elf-fashion, except on Shadowfax, said Gandalf. But Shadowfax will have no harness. You
do not ride Shadowfax: he is willing to carry you --
or not. If he is willing, that is enough."