Deathfire Touch lacks clarity
- Shows damage per 4 seconds instead of per second
- Does not stack up on enemies --> We have no idea how much damage it actually does.
The mastery tooltip should be refactored to show its dot damage in one second. Then exceptionally state: aoe affects last double/2 seconds, and single target lasts quadriple/or 4 seconds.
That way when one considers the mastery they're only thinking upward (easier for me at least)
ALSO IN GAME, why isn't the dot using the new ramping up combat text?????????????????? (cannot express enough??)
ALSO IMO, every damage mastery should state damage done in their tooltip during the game. I know it's not an ultimate conclusion on which is best, but it should help with assessment for those who are curious.
The reason why it is unclear is to hide the fact that it does utterly shit damage except for 
--> We have no idea how much damage it actually does.
I'll tell you exactly how much: Shit. With just base MR and Hp5, it's pretty worthless early and just barely mediocre late even with full penetrations.
I'm sure you can see how much damage DFT does exactly at any point in the game by pressing tab and hovering over the DFT icon beside your champion. If that's what you mean.
Anyway I agree I can't notice the damage at all, there's no indicator for it, or a mention of how much it does for AOE and DOT.