Sure, same goes for Bastian, each special attack can be boosted with numerical cards with the special symbol. Fists only cards won't work for a special attack.
Remember each attack is resolved separately, so each boost card can only improve one attack only.
For Bastian this is true, but do keep in mind that when boosting an area effect you have two choices:
a) you can boost the whole effect (when same boost card works for for every square of the area effect) = is very powerful with Elisa's torrent of fire, for instance
b) you can boost just one part (one target) of the attack. Which is sometimes required when area of effect contains friendlies.