I want to make sure I'm doing this right.
This is RAW, I know this is not RAI.
Concept: as much Hellfire Blast damage as possible; getting useful invocations, and lots of them, early.
At level 12, the build would be:
Binder 1 / Warlock 6 / Legacy Champion 1 / Uncanny Trickster 1 / Hellfire Warlock 1 / Legacy Champion 1 / Uncanny Trickster 1
With all three bloodline levels bought off already of a custom Major Devil Bloodline.
So first, on my understanding of the mechanics of the Bloodline levels:
1) after you spend XP on it, that is when you get the "virtual levels" on other classes, so basically, it's treated like a LA buy-off that has a "kicker effect";
2) while it may be RAI to only apply this to one class, RAW it applies to all classes.
So, my thought is, HF, LC and UT, all of which state that you "add your levels in this class to X, for X purposes", designating HF as the boosted class from LC and UT. The Bloodline increases your levels in each class for purposes of "calculations". So if I'm reading this right: then you get to add the Bloodline to Warlock, which only increases the range and caster level of the EB; add it to HF Warlock to gain + 3 levels to the advancement of Hellfire Blast, and Invoking, which means that from this you basically treat your Warlock level as 4 higher for you Invocations known, EB damage, et cetera, instead of just one from HF; added to LC for another +4 instead of +1 as normal to HF Warlock; repeat to UT for another +4 instead of +1 as normal to HF Warlock.
For +11 to Hellfire Warlock, totaling 12. (One for class level in HF Warlock, one for class level in Legacy Champion, one for class level in Uncanny Trickster, 3 for virtual levels from bloodline to HF Warlock, 3 for virtual levels from bloodline to Legacy Champion, 3 for virtual levels from bloodline to Uncanny Trickster.)
Meaning you'd choose your invocations for Warlock as though you were a level 18 Warlock, and your Hellfire Blast would deal 32d6 damage (8d6 base from level "18" Warlock, plus 24d6 from level "12" Hellfire Warlock).
While this breaks RAI, I like this concept, because of its balance.
Why? Most of the Warlocks invocations are not that powerful when you get them, but like this, you can actually make use of the class. The damage might seem high, but even if you max out the use of the scepter for +4d6, Greater Chasuble for +2d6, and Mortalbane for +2d6 getting 40d6, that is still only going to average 140 damage, which this guy will have had delayed progression in the party from spending XP on Bloodlines, so he would be going up against CR 14's, which usually can withstand over 250 damage.
So, question time:
A) Is there any glaring misunderstandings that I am having on application of Bloodline Levels?
B) Are there any disagreements about my assertion of the balance of this?
C) Any other comments?
D) Would you allow this, for this build?
E) Would you be so stupid as to allow this type of Bloodline + UT / LC abuse to apply carte blanche?