Voidbearers and Piety - Type of Elemental damage?

Do voidbearers (the blue frog things in the docks) deal fire damage or cold damage? They are blue and their breath is blue so I assume cold, but a friend thinks it's fire?

Piety's fire/melee form...is it melee damage? or fire damage? both?

This stuff is pretty important to know for harcore, yet there seems to be no way of knowing other than going with intuition.

Voids are definitely fire damage. I play a fire/summoner witch and spectring them while debuffing with flammability leads to some insane face melting.

edit: As for piety I couldn't tell you. I have never been ignited by her melee but for the most part she never gets close to me due to quicksilver and skele totem decoys.

yea i was also confused by the fact why would fire be blue, i was convinced its cold and stacked cold res till i realized it doesnt really freeze/slow me

Ok what about Piety and her melee/fire form? Do I need fire resist or is it useless?