Well you ARE talking about a Scythe, nothing can survive a crit from one in most cases anyway. The damage does multiply (just like a Smite). Using a x4 Crit weapon probably isn't a good comparison, much less a flaming burst one.
Odds are that attacks going to kill something without ANY strength bonus, at that point its just overkill.
I'm not sure where you're getting your numbers from a flaming burst scythe wielded by a character with say an 18 Str would do:
30 Flaming Burst+32 Scythe+24 Strength for a total of 86 barring magical bonuses.
Its alot but, the odds of getting a crit with a RetStrike is pretty small (you have to declare it before you attack).
Edit: ok just saw the other 6 damage, from the flaming part of flaming burst right? Ok 92 damage (min 96 if its +1). Its alot, but like I said you have to basically roll a 20 to do it. Not to mention you've got to own at least a +1 Flaming Burst Scythe. This is why scythes are cool (since they don't have much else going for them being 2 handed weapons that do pretty low damage).
If you think its too much make them roll the fire end, most of the time its not going to matter (since the situation is pretty rare as is). But it definately works for the critical from the weapon's damage.
