Heat from Jelly King runs...
I've been trying to get this 4* Avenger to level 10 heat and it's just taking forever. Someone told me that if you do one Jelly King run it'll get up to 10 but it's not even close... last run with 3 other people in it I got like 1.5 levels, from 3 to 4.5. Is it better solo? God this is annoying.
And yeah, I unequipped my other weaps so it's only the Avenger getting heat.

Actually, a full t2 jelly king run used to be able to take a four star item all the way to 7-8 in a 3-person party. It seems like they lowered it, however. I did exactly this with five different items, so it's not "hype". Jelly areas give more heat/crowns because they contain more enemies per floor.
Wow, it's ridiculous how little heat you get now. I just did another run and I got maybe 1/3 of a bar for level 6. Holy crap... this is going to take hours upon hours.
depends on how many items u are leveling, the more gear ur leveling the longer its gonna take since the heat is split up.
I don't know if they've changed it to reduce it or what, but it's worth realizing you're levelling a 4* (tier 3) item in a T2 area. You might get better heat per energy values if you tried grinding the first half of T3. I don't know for sure, but it's something to try once and see.
EDIT: Welp, survey says NO. So don't do that.

the first half of T3 gives absolutely horrid heat ammounts.

Yeah, T3 heat/crowns are really bad in the first half. My bar doesn't really even move after clearing 19-22 and even an arena only nets me 1/8th of a bar on higher levels.
As for JK, it feels about the same to me. I was leveling weapons from 1-4 on level 15 and I still get about that much.
Have friends that will let you mooch of them at D15. Offer to go solo if you must. Just remember to return the favor :D
edit: oh, and don't die
From what I've seen, generally speaking, odd strata are horrible, even strata are good for heat/crowns. (That is, things get way better after the waypoints.)
What is it with all this hype when it comes to jelly king heat and crowns? People forget that the primary goal of hitting the jelly king is for the TOKENS, haha. The normal mob drops along the way are lucrative, yes, but not to any extent that can't be matched by several arenas, danger rooms, graveyards, and treasure vaults.
But, yeah, 1-10 heat level on a 4* star item in a single tier run of ANY combination of levels is absurd.