Looming Devastation

This spell casts {1} less to cast for each card you
own in exile.
Looming Devastation deals 1 damage to target
opponent for each tapped land they control.
Groat was still a novice when it came to augur-magic,
so when he passed the Chamber of the Guildpact and
sensed the vaguest whiff of desert air on the wind, he
didn't give it a second thought.