Elf that has STSF. For the purposes of this exercise let's assume something benign like whispers or soul. He'll be Maran, and be a whip spec. Assume the elf is wielding mithril wrath daggers, or normal Maran light daggers. Progged gear also.

Fights another dagger/whip spec, either drow or duergar, with fires of adversity. For the purposes of this exercise, this dagger spec either has maelstrom or balance, but not both fires and STSF.

In this situation, does STSF become a liability for the elf because fires makes the other dagger spec tank better, making for more concealeds?

Or is it just prolonging the inevitable?

Will goodie prog gear make this all moot anyway?

I'm going to say that the duergar having fires is going to do okay, but will ultimately lose in the long run.

Let's take out all other variables except:

Elf - dagger/whip and stsf
Duergar - dagger/whip and fires

The duergar is going to HAVE to deal out the damage quickly on the elf BEFORE striking has a chance to build up. Let's say the elf builds up three observes by the time fires kicks in. At that point, even if you're tanking better, he's getting at least two or three concealeds per round. Your skills are going to start missing because of the gayness of STSF, your escape will be blocked off, and he's hitting you like a monster.

I've seen a few logs of STSF vs. STSF. It is supposed to give you better defense and better offense, but with two people having better offense, it cancels the defense out and they both hit each other often even without concealeds. I think it would be the same for fires where the defense is cancelled out.