As Frostboil Snarl enters the battlefield, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters the battlefield tapped.
![](/symbols/T.svg)
: Add
![](/symbols/U.svg)
or
![](/symbols/R.svg)
.
"We're on the Thames. The last great Frost Fair. 1814, February the 4th."
—The Twelfth Doctor