[0]: Create two 2/2 black and green Wolf creature tokens with "When this creature dies, put a loyalty counter on each Garruk you control."
[−3]: Destroy target creature. Draw a card.
[−6]: You get an emblem with "Creatures you control get +3/+3 and have trample."
If lethal damage is dealt to one of Garruk's Wolf tokens at the same time that Garruk's loyalty is brought to 0 or less, Garruk is put into your graveyard before the Wolf's triggered ability can save him.
If the target creature is an illegal target by the time Garruk's second ability tries to resolve, the ability won't resolve. You won't draw a card. If the target is legal but not destroyed (most likely because it has indestructible), you will still draw.