If your library is empty, discover fails to find a target and doesnt resolve
Just like the Necrite, the Mindstab Thrull appears to be some kind of a kamikaze warrior, dealing 'mind' damage -- represented here by forcing your opponent to discard cards
Maybe even "I will not forget one line of this - not one day, I swear?" Uh...not so much: Candy Grapple "Don't you mean poisonous'
The two overlap on some hefty card draw spells ([mtg_card]Incendiary Command[/mtg_card], for example), but you could also pull apart the precon and build distinctly different decks around each respective commander
On the front side, this is a five-mana removal spell that nets you a Treasure
But you may want to try having it on the battlefield tapping and untapping to churn through your deck and make a lot of Pilots