Stop nerfing DoT mages; nerf deathfire touch (the actual problem)

tl;dr: Deathfire Touch broke Brand Swain Malz and Anivia, so instead of nerfing them nerf DT properly. I'd suggest making DT apply only on the first instance of damage from a DoT.

There are nerfs on PBE to DT, but the nerfs to the champions DT made problematic have not been reverted.

1. Riot introduces something that breaks certain champions
2. Riot fixes this thing that breaks certain champions
3. Riot proceeds to nerf the champions anyways ????????

Furthermore, the present set of nerfs to DT on the PBE do not address the issue. It is has been pushed away from being a viable choice for non-DoT mages, while not properly addressing the interaction with DoT spells.

Riot has pushed nerfs to Brand, Swain, Malzahar, and Anivia to the PBE lately. This is presumably in response to the large jumps in winrate these champions have received due to the recent mastery reworks, particularly the synergy between DoT spells and the Deathfire Touch mastery.

Their is nothing inherently overbearing in the kit of any of these champions. All four exemplify what Riot has often referred to as the Talon effect; small, dedicated playerbases experiencing success on a champion because of their familiarity with the champion. Aside from Anivia (who came into the competitive scene for her strength at containing juggernauts), none see competitive play. They were all perfectly acceptable champions until the mastery rework pushed them into the OP range.

Instead of nerfing these five champions and alienating their very small playerbases, why not just fix the root of the problem: the interaction between DoT spells and Deathfire. It is very tangibly this interaction that has given these champions such a spike in power and popularity.

No Brand/Swain/Malz/Anivia players were asking for buffs and now these champions are being nerfed because Riot decided to meddle with the mastery system. Instead of making sweeping changes (removing a huge chunk of Swain's range, slashing Malzahar's tank melting ability (he's one of the only tank-shredding APs left! With the prevalence of juggernauts, midlane needs to keep this answer!), etc) to all these champions... simply fix the broken part of the system. Deathfire Touch.

I would suggest applying Deathfire Touch only on the first application of damage from a spell to balance the problem. This would turn the interaction between Malz E + DT into the same one as Vlad Q + DT, thus fixing the problem.

Thank you for your consideration.