Well, it's sad that Geirskogul is on a 10s cooldown, but kinda expected. What I'm interested in is if you could somehow get 2 Geirskoguls in a BFB due to how Buffs fall off... That would be absolutely nasty.

As for 30s Duration.... Depending on the exact amount Geirskogul consumes, you might not need to pop BotD just before Chaos Thrust either.