According to the coh hero planner v1.5a Fire sheild has resistance vs Disorient, and Plasma has resistance vs Hold and Sleep. Im not sure how good this resistance is, but since its a primary tanker pool im guessing its quite good. Now that covers all the toggle shut off effects doesnt it? Then you wouldnt need acrobatics, right? Also, you leave out hasten and combustion till way latter. These two skills, maybe even hasten alone instead of swift (at lv12) would make this build WAY more effective in those earlier lvs. Is there another reason you got swift so early and hasten so late? i couldnt imagine why... since you arent even getting stamina till lv26...
This is an AOE fire tank build right? The more AOE dmg you do, the faster they fall, which means u require less defense and kill faster (faster xp). I hear you speak of dmg over time so much, emphasizing your need for very good defense. Fact is fire tanks will not tank as well as say invul, no matter what you try (except maybe at very high lvs when u have tough and weave 6 sloted). Fire tanks make up low def with great offense, yet you dont utalize it untill much latter in this build. Adding Build up+hasten+combustion for example would nearly double ur dmg output (for lvs <30). Maybe its just your style to sit there and watch burn over and over not having to worry about time or your hp bar, but in my opinion the build seems a bit over defensive. Oh, and the offensive build below seems too offensive; too many attacks. With perma hasten +build up you dont need that many attacks. Im just saying why not get the essential AOE powers (like combustion) +hasten, maybe even build up sooner? Maybe its possible to make an effective tanker that is more balanced, just like you said "people think fire/fire tanks are the most balanced in the game". Go ahead, show me a build for one

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PS: This is my opinion, im a critic by nature, pls dont flame.