Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)
As long as Thundering Mightmare is paired with another creature, each of those creatures has “Whenever an opponent casts a spell, put a +1/+1 counter on this creature.”
Near Mint - $900
Lightly Played - $700
Moderately Played - $600
Heavily Played - $600
Damaged - $500
Near Mint Spanish - $900
Lightly Played Spanish - $700
Moderately Played Spanish - $600
Heavily Played Spanish - $600
Damaged Spanish - $500