I summoned this pet against a cursed treant in Loping Plains. It lasted 23 seconds, hit 48 times for a total damage of 65,882. Max hit was 2269. It could be healed. Considering the druid mana-free instant AA nuke routinely hits for 148k when maxxed out, this isn't great extra firepower but every little bit counts. The only slightly pricey component is a Relic Fragment. My 300 tinker made 9 in a row with one failure. They do stack, too. Of course, there's the rub. To use this regularly you need a tinker to make you stacks and stacks and stacks.
The target mob was level 75 and the pet could have solo'd it entirely, had it lasted long enough. It vanished with the mob at 15%. I do want to test its damage output against mobs that would give a level 105 player experience. I will post results here.
Ultimately this is more for the fun of it: so other players will ask you "where did you get the Arc Worker pet?!"
Edited, Jul 31st 2015 8:43am by Sippin