Thanks for the replies everyone.

I've found that if you do know when to use Shield Bash, it's actually a pretty nifty tool to have. For example, you know that the Manor Maidservants in Haukke Manor will always open with their Dark Mist AoE attack, so it's safe to use Shield Bash then as you wouldn't have begun using your combo yet. Another use for Shield Bash is when you have only one opponent aggro'ed (ie. the Manor Servant) - I've been able to disrupt his AoE attack every single time without any problems. Although it breaks my combo, but that's not a problem as I have a lot of aggro to begin with already. If I have to stun him with the Jester alive, then I just break my combo to stun him, because I've applied a full round of FB -> SB -> RoH combo on each of them once for the initial enmity. I've read that the same stunning principles should be applied for Dhorme Chimera, so I guess this is good practice of knowing when they will attack, and when to disrupt it.

Sometimes the DPS isn't able to output enough damage, and eventually my TP runs out. Such was the case with my Brayflox run yesterday with the last boss.

My current rotation is:
1. Pull with Shield Lob. If there's a ranged mob, I'll use Shield Lob on the ranged one, and then run to it, to bring all the melees to it as well.
2. When all the monsters are grouped together, I use Flash once.
3. I use Fast Blade > Savage Blade > Rage of Halone on marked mob #1. Then Flash.
4. Swich to mark #2. Repeat the combo. Use Flash once more. If there's a total of only 2 mobs, I don't use Flash, and switch to #1 and repeat the combo.
5. Switch to mark #3. Repeat the combo. If there's only 3 mobs in total, I don't use Flash after this - I switch back to #2 and use the combo on it. By this point, #1 should already be dead, or close to dying.
6. Repeat the above, until 2 mobs remain. When 2 mobs remain, I simply alternate combo-ing them without using Flash.

If there's more than one ranged (ie. 3x Servitor Lanterns and 1x Attack Hound in Haukke Manor 2nd chest room):
1. Identify the 2 closest ranged mobs, then use Shield Lob on one, stand between them and use Flash.
2. Perform combo on 1st ranged mob, use Shield Lob on the farthest one, and use Flash.
3. Repeat until the first 2 ranged mobs are dead. Then go for the 3rd ranged mob.
4. Use same one above where I rotate the combo between the 3rd ranged mob and the melee mob.

Seems to work out fine for me now. Thanks for the advice guys!