I don't know why this would be that hard to understand, or how y'all didn't think it would change things drastically. Of course poison/bleed/quick sand will still be effective on him. But let's stick to fire since every war he's in will have fire, while having other DoTs is a random factor determined on other rules and players rosters.
You introduced a fire tank, as this months premier monster at the usual premier price. Someone like me comes along, thinks "oh this could be cool especially since his element (the one he'll for sure always be fighting) only has one DoT that can stack on him."
Then, the very next week, before I can even hatch all my eggs and get him to 130, you change mechanics so that the element that he will always be in war with now stacks those DoTs. They didn't before. You changed the mechanics. I get one stinking war in with him and now he's pretty useless on defence in elite wars which was the whole reason I got him. Elite wars are filled with VIP and now the new nemesis, both of which will melt his face off with double DoTs that ignore his fancy high health you promoted him with.
You know what, whatever. I don't know why I'm bothering to explain this to a monster designer. If you don't know what you did to nerf your newest premier monster a week after you released him I can't make you see the light. You guys have fun