Question about Eldritch Blast save DC's

[skunk3]

Question:

As a Warlock, if I use Eldritch Cone + Vitriolic Blast what is the proper way to calculate the reflex save needed to take half damage? Would it be 10+invocation level (the cone is 5th or 6th level)+CHA mod? Would I also add the level of Vitriolic Blast? Would I use only which is higher of the two or JUST the level of the cone itself? I am under the assumption that it would be 10 + cone invocation level + CHA but I just wanted to be sure.

[Troacctid]

The level of the blast is equal to the level of the highest level blast shape or eldritch essence invocation applied to it. So yes, you can improve the save DC of a blast shape by adding a higher-level eldritch essence to it (or vice versa).