The biggest weakness of the deck is its slowness
Since Anrakyr lets you cast the spells from your hand or graveyard, you even get to set it up with all of blacks powerful tutors like Entomb and Vampiric Tutor, or you can replay the artifact if your opponent destroys it
And by spells I mean creatures, sorceries, enchantments, enchant creatures, instants, interrupts, horses, tractor-pulls, and phosphorous
Whites color identity revolves around smaller creatures that lose a lot of ground in a multiplayer format where you face down three players at 40 life
Ambush works with your attacking creatures, though
This one mana threat has haste and prowess, attacking immediately on the turn it's deployed and growing by +1/+1 for each noncreature spell cast