How about this, you're wrong. Sheltron is fine. NO tankbusters crit outside of forced crits like the stuff from Diabolos Hollow and Halicarnasus where it's based around that... so then... use something else and plan sheltron for something other than that one thing? It's called planning mitigation, something you need to learn as a tank, just like planning heals on a healer... oh the horror.

Sheltron is amazing, and is on par with two personal CDs since you can stack 100 gauge for it. It's not static like a cooldown like Camo, you can plan the two charges for two different things.