Ah, but therein lies the rub. Check the power:
Fiery Bolt Warlock Attack 3
You call up a bolt of golden flame and hurl it at your foe. Anyone standing close to him is burned as well.
Encounter Arcane, Fire, Implement
Standard Action Ranged 10
Target: One creature
Attack: Constitution vs. Reflex
Hit: 3d6 + Constitution modifier fire damage, and creatures adjacent to the target take 1d6 + Constitution modifier fire damage.
Infernal Pact: Creatures adjacent to the target take extra fire damage equal to your Intelligence modifier.
There is only one attack roll to hit. So would the crit max the damage for the adjacent creatures, or is there damage un-Crittable? (is that a word?)