Indomitable Wurm

Indomitable Wurm costs {1} less to cast for each Desert you control.
{1}{g}: Indomitable Wurm gets +2/+2 and gains trample until end of turn. Activate this ability only if you control a Desert and only once each turn.
Within the walls of the Menagerie, it was restless.
Now that its outside, it is reckless.