I have seen devour used wrong as well. Example.. I have 3 creatures on the field.. say a 5/2, a 15/3 mutant and a 0/3 devourer.. the AI eats the 5/2?? dies due to this..
Also, using blessing on the wrong creatures.. I was playing in Arena with someone using a photon and a bunch of lava golems. I antimattered 1 golem and it slowly became a -1/9 or something and the AI used blessing on a photon to make it a 4/4 instead of making the golem + attack. ive seen this with deja vus i antimatter and they put it on a different creature. i can understand that its because of a lower attack if done on the - attack creatures but a lot of the times the - creature is saving me... especially when they are multi attackers. 1 de ja vu = 8 damage.. 1 dragon = 10 .. almost cancels out. 1 blessing on the proper creature means im taking 4-5 damage instead of healing 8