Originally Posted by
Loriac
This seems to be a reflexive answer, rather than one that considers the actual spell power changes that have been made.
Firstly, quoting BB crits (against which the mob didn't save) is really showing the best possible outcome, and doesn't factor in frequency and evasion.
With the spellpower changes made, empower adds exactly 56.25 damage to a blade barrier (75 * 0.75) on a non-crit. On a crit, assuming the full kinetic line and greater arcane lore, you have a 2.5x multiplier (this is assuming that kinetic lore doesn't affect bb, only arcance lore does, which I think is correct), or 141 damage [note that this is ~10% of the spell damage you listed, i.e. empower as a feat is now adding 10% damage vs. not having it]. Assuming 18% crit chance, this yields expected incremental damage of 72 where the mob doesn't save (36 on a save, 0 on an evaded save).
Blade barrier is the only arti spell you're likely to be throwing around that has empower on it, so you're purchasing this feat purely for that incremental 72 damage. And, as mob saves increase in epic content, you're less and less likely to see that incremental gain fully.
Also note that the more likely scenario is that a geared arti will have both tovens and lucid / archaic, and therefore will not have a 19ap investment into Force. Assuming a 9 pt investment instead (7/1/1), you're now looking at a crit multiplier of 2x including item, and crit likelihood of 13%. These numbers obviously make empower less useful.
My overall point is this: empower is definitely not a no-brainer feat for an arti, and has to be weighed up against what you don't take instead. I'd rather take any +1 DC feat instead of empower for example, because that will make BB's more likely to hit for full rather than half or zero damage, will add to cc capability with prismatic / tactical, and will add to rune arm damage (again via lower save frequency from mobs).