Deathfire Touch feels weak
In the early game you hardly do any damage by Deathfire Touch. If the enemy has at least 40 MR, the mastery does literally 0 damage.
I wouldnt say anything if it was supposed to be a late game mastery that needs time to grow up. But its quite the opposite. In custom game with 881 AP I was doing 34 magic damage per half second (on bot with 30 MR, actually 0 bacause i penetrated it with MP), which feels rather unsatisfying, not to say that aoe abilities deal half the damage.
My suggestion is to increase the AP scaling and let aoe abilities to do full damage because this mastery is used mostly by mages whose majority of abilities have aoe nature anyway.

and
. It sacrifices a fair amount of damage, but it helps even "burst" mages do decent DPS later on. I'm sure this strategy would be frowned upon by a lot of people, but after doing it so long, my mage pool just seems so clunky without it.

(well she can use either one imo)
thinking that I was going to have