Frost Bomb is used to lower boss resistances. Try to pre-place before a boss spawns and keep up the stacks as it adds a lot of dps. Keep in mind a lvl 3
Frost Bomb will only work on bosses lvl 25 or below, so you will eventually drop it as you don't have the int to keep lvling the skill. Once you have
Voltaic Mark, you can drop frost bomb for less buttons.
for
Lightning Rod you can either use Concentrated Area or Lightning Attunement, this just depends on your gear (if you have a bunch of fire damage/cold damage to attacks, than Lightning Attunement loses a lot of value). Once you get your 1st orb for a 4 link, you want to add on Multishot II.
On
Lightning Arrow you want to swap Innervate for Chain II on bosses. (if your rod is only 3 link, than swap Lightning Attunement). - Note only do this when your lightning rod is 4 linked with Multishot II, otherwise chain doesn't feel good to use.
Barrage can be used to quickly setup rods or burst down a boss on spawn (pre-place rods into barrage
Lightning Arrow)
Electrocuting Arrow is only used for bosses and has a 25 second duration, so it's a set and forget type of skill, it does get consumes on electrocuting an enemy, but bosses should die in the 1st one.
Voltaic Mark combos with
Electrocuting Arrow, giving you extra lightning damage when you electrocute an enemy. Same deal here, only use it for bosses.