Deathfire: The more I play...
The more I realize just how bad this is on anybody not named Brand.
At the highest point for Deathfire, once you get to 700 AP, it deals 146 per poke spell. Except half that, because almost every harass spell is universally some kind of AoE. Base damage for Thunderlords is 180 (and then +70 more for scaling). You need to get off 5 solid seconds in the "best" endgame case for death fire to match thunder lords, meaning even in endgame it is only marginally better, and thunder lords is 'significantly' better at all other points in the game.
Lvl 6 all in for example: 60 Base. Lvl 6 Deathfire, if you have 100 AP, 6+20=26 per 3 seconds.
Thunderlords doesn't 'scale' as well, but the base damage alone of Thunderlords just outclasses Deathfire.