I have been through the same line of thinking at the present time.
I have been leveling then playing as LL according to Nitz's guide and started finding some difficulties
1. LL has too many areas where you have nowhere to stick it.
2. Tiefling does not give enough in return for so many points. Defence = 0 is bad, but at least I can run. I wonder if I need defence with new passive anyway?
3. Phase Bomb has so many issues. Can kill self (when using Shadow Refuge) and summons and it seems it may not break immunity anyway since only -25% (Some monsters have > 125% immunity???). And the mechanic of the skill is too slow in combat.
So I was thinking along same lines as your build. But I have some thoughts/comments
1. Why not at least 1 point in Vampiric Icon?Possible secondary skills:Hailstorm
2. If using Fire Sentry as backup skill I think I would not want a fire merc. So I am also considering a barb merc (since no PB). is that a good idea? Abjurer is pointless if using Light Sentry and I think the cold Act 3 merc is not very good still?
Act 1 merc possible but it would be useful to have a tank in front of a caster. I am assuming that the summons will still be weak even without PB since they are not buffed with minion resists or life (perhaps this could be a good place to use any available MO space?).
3. My expectation with WotG is that it would give the +10% per level to lightning damage from spells but the flat damage is weapon damage so we would not get that (except when using Shadow Refuge of course).
4. It may also make Shadow Refuge not so worthwhile since Nitz recommended 50% damage reduction between this skill and others (what is EQ by the way?). Again, perhaps not needed with new passive.
5. The overall downside is giving up a 1 point secondary skill such as PB and replacing with Fireball Sentry (and WotG needs more points since it will not be a 1-point skill I imagine). But we have some free now from Tiefling of course. So. Regarding choice of secondary skills...
from amulet. It could also be a useful helper skill for bosses.
Unfortunately I wanted to use Black Dwarf as amulet (but its Supernova skill would not work here as alternative to Electrofield). Psionic Storm is possible. It has a small area of effect and costs a lot of mana especially when it has to be cast many times on fast moving enemies. Overall it does seem just about ok.Psionic Storm.
Also gives access to psionic Scream which may be useful when lots of monsters come all at once.Fireball Sentry.
Many skill points and may need some gear and MOs. Is it effective without +fire %damage and -enemy fire resistance?
Overall I'm tempted by Psioinc Storm since there is no need or possibility to gear for it (magic damage). Is there a reason this would be a bad choice? Sorry for so many questions. I need more experience at this game as yet.
By the way. What did you mean by "I have to buff twice now" (with phase bomb)?