So this is more to the "general purpose" part, not so much the "bragging" part, but I didn't want to create a new topic just yet and I wanted to share my test into Chaos Avatar giving XP.
So I did 2 test runs (very basic Eastern Tundra, no VT, Dwarf Tinker prepping JJ in both cases). I tried to play similarly, i.e. going for kills that only level me 1 level, and trying to slow everything (I managed to do that, except for 3-4 golems in both cases). I deliberately did not use IMAWAL/Alchemist Pact/Balanced Dagger/etc., to keep things simple.
Exhibit A: run where I *did not* take Chaos Avatar:
I earned 266 total XP, 101 of which is bonus. The 101 bonus XP is thanks to 64 bonus from killing high-level monsters; and 37 thanks to killing monsters slowed. The (266-101=) 165 base XP is explainable by: 149 XP for the standard 38 monsters; +6 for Glenrick; +10 for Blahblah.
Exhibit B: run where I *did* take Chaos Avatar:
I earned 324 total XP, 110 of which is bonus. The 110 bonus XP is thanks to 74 bonus from killing high-level monsters; and 36 thanks to killing monsters slowed. The (324-110=) 214 base XP is explainable by: 149 for the standard 38 monsters; +5 for the "free boosters" sub monster; +10 for Blahblah; and +50 XP for the Chaos Avatar I took at Level 10, at precisely 0/50 XP.
"Thinker", just without the "ache".