1.19a Patch Notes

[Arcell]

That was possible before 1.19, just slightly differently.

let me explain the difference.

POST 1.19 PLing
group consists of 1 level 50 and 7 level 35s
the 50 kills everything while the rest watch, the level 35s get more exp than the level 50
everyone got exp

PRE 1.19 PLing
group consists of 1 level 50 and 7 level 1s
the 50 kills everything but the level 1s only get exp if the level 50 gets none or very little
only the low level chars get exp

And now:

Post 1.19a PLing

2 groups, the low level group and the level 50(s) powerleveling them.
The low level group engages an enemy (likely within 10 levels of their own), claims enemies, level 50 kills them and the low level group gets full EXP.