Disclaimer:I've never even gotten access to Tavnazia before so this strategy is mere speculation as to what to pull and what to watch out for.
Start with the Bugard NM at the start Directly across from where you enter. Work Quickly as you only have 15 mins from the point the glass is broken till you time out. Unlike all the previous zones where you avoid fighting without your Subjobs for the most part, Tavnazia has 2 NMs that must be killed to unlock subjobs and they can easily wipe the alliance.
Move up one floor and have a THF Flee and run around the circle, at some point the alliance will be pulled into Phantom Worm, Just toss up Protectra, Shellra, and Barstonra, and goto town. Every time this work uses a TP move he will draw in the alliance to make sure it hits everyone, try to recover from each TP move with AoE cures and take him out quickly. With Phantom Worm down you are 1/2 of the way to getting your Subjobs back.
Go up another floor and this time have the THF use Perfect Dodge and Flee, He does the same deal running around the circle until Nightmare Antlion pops out of the ground. This guy has nasty poison and silence so everyone use Antidotes and Echo Drops when you get enfeebled and take him down slowly... Antlions don't really have huge Damaging TP moves, they rely on stat ailments to give them the edge. With the Antlion Down you should now have your subjobs unlocked. Antlion is also a 30min TE.
From this Point Choose your focus, either Beaucedine Drops or Xarcabard Drops, Lol some choice...
If you choose Beacedine, Head back down to Floor 2 and work your way towards either the AH or Moogles. You'll be fighting Hydras, which unlike the Beaucedine Glacier ones, these can be slept so they aren't as big of a deal .Once you clear out one of these areas work towards the upper connection peice until you see a ???. The ??? is a 30 min TE but also repops everything you just killed so be ready for some action when you click it.
If you choose Xarcabard, Stay on the 3rd Floor and work your ways to one of the 2 offshoots, You'll be plowing through Demons and Taurus Monsters so keep on your toes. Taurus as you should remember have AoE Poison, AoE Def Down (very potent), and AoE cone based Doom (Mortal Ray). Tanks and Melees should bring Holy Waters if they don't want to die. Once you clear one of the 2 upper areas work toward the other on the top path and you should see a ???, this will repop everything you've killed so be ready when you check it.
If you have enough time to clear both by all means do so but it isn't easy. After If you still have time you can try to sneak by the Umbra Diabolos (NPCs). If one Sees you (sight based only) they will move towards the Misareaux Coast and Lufaise Meadows entrances. They will link any others along the way. How Many Bosses you Fight is dependant on how many the alliance aggros. Assuming none aggro, you should only have to fight 1 Diabolos. If you link all 4, 4 Diabolos will pop, you will need to kill all 4 to get win, if you only aggro one you only have ot kill 1 to get win.
the Nightmare Bugard should be pulled ASAP, because you only have 15mins upon breaking the glass. Time +15
Have a THF flee around on the 2nd floor till he pops the worm, Make sure to have protectra shellra and barstonra up. And remember SMN, and BLM cannot heal themselves until both Subjob NMs are dead. Watch out for its TP moves which it draws in the alliance for, be ready with AoE cures to heal everyone back up. Subjob NM 1/2
Move up to floor 3 and have THF flee around the 3rd floor circle with Perfect Dodge until antlion pops up. Antlion has Venom Spray (-50hp a tick poison (antidotes recomended)) and Sandblast AoE Blind + Silence (Echo Drops Recomended). Once he goes down youll have your subjobs back. 2/2 Subjob NM, Time +30
Pull 004&005 which are groups or 3 bees each. Nothing special shouldn't be too rough. 006-009 are Hydras so be ready to take them out quick, Watch out for Aegis Schism is a very potent Def down, Erase that immediately. Have WHM's stand in range but not infront of the monster to esuna Dancing Chains. SMNs can counter Chains with Earthern Ward and SCH has AoE Erase.
009 will pop the 30 min TE for 2nd Floor. Once killed all the pops on the way back will come back as 036-032
Read 004-009. 037 pops between the 2 bee pulls, so be careful of a massive link here. Same goes for Xarcabard drops pulls.
again 068&069 are bees. This time were fighting demons mixed with Taurus, watch out for AoE doom and Poison. Taurus pop on 072(x3)&074(x3)
Remember clicking this means you gotta work backwards but you do get 30mins for it!
098 now pops where bees are making this pull pretty rough but the rest of it is just reverse.
Sneak past the Umbra Diabolos on the 2nd Floor to Misareaux Coast or Lufaise meadows. Yes this means the whole alliance, if you manage to get back there without any aggro, aggro the last Umbra you see to pop 1 boss to fight.
Irrelevant section, the monsters you fight dont have jobs.