That is correct, plus any surviving mobs will not just stand there anymore and wonder who just boomed them, they will come running straight for the dwarf and attack him/her. So, previously you could boom them, then summon a new big boom and send that in and so on, but now you will get attacked after the first one. And that means you cannot pull big trains anymore (because you just will not survive it), you have to take only a few mobs at a time. I do not play a dwarf, but I would guess it simply is not worth it anymore because of these changes. It is slow and the summon costs quite a bit.
Powerlvling most likely, and it still works. Big boom lvl 2 1 shots mobs at Tanor Canyon area with emp and shots, and with a skilled puller it can hit a load of mobs at a time. Thought it didnt hit more than 20 but it seems to hit alot more >.>
I'd prefer an ES tho, as the summons AoE didnt get nerfed in any aspect so it's much better at plvling now, especially with the added "move" command.
right after the first boom, have the mobs aoe slept by a spellsinger or a sorcerer, then boom them again.
1 boom generates enough xp for 1 reasonably happy ws or 1 fairly unhappy ws and 1 really ****** off spellsinger
big booming is not feasable in c4, boom pulls less mobs, cost a hell of alot more and without a tank a healer and another nuker/ws you cant even kill the mobs without dumping all agro directly onto the ws
do not even waste the sp on the skill unless 1 hitting lvl 4 noobs in the arena after someone has slept them is what you want to use it for