My most succesful promyvion run went like this.
Party was SMN, SMN, SMN, RNG, WHM, PLD.
The RNG would widescan for Memory resepticles, on our way too the memory resepticles all party members where extremely careful.
For 1 party aggro on the 2nd 3rd and 4th floors mean death.
Once at the memory resepticles the summoners are to send there avatars after it allowing them too get all the hate from the strays, everyone then stands back and the RNG and the PLD pull strays and kill them one by one.
If they dont pull the strays off the avatars, if the avatars die, all the strays will all rush towards the person with the most hate.
While moving around floors 2-4 taking it easy is the biggest key too success, dont take too many risks.
If one person wants too move ahead of the group too scout ahead thats fine, but if this person gets aggro, he/she should find a safe place too die so the whm can raise him rather than put the whole party at risk. a BLM can come in handy in this sort of situation because of there ability too tractor a dead party member.
In some places getting aggro might be extremely hard too avoid, in such cases, follow the strategy above or if the party thinks they can take it, it is extremely important that it doesnt cause a link. finding a camp and having someone pull the enemy might also be a good choice.
For potions and food etc....
Melee should bring there standard food.
For mages yag drinks and pies are perticularly useful.
Every party member should bring either a reraise scroll or a potion.
A WHM should bring as many as possible. If the WHM dies without reraise on and there is no other WHM too raise, then its... GAME OVER.
You can only carry 1 reraise potion at a time but if its possible have party members keep them and trade them too the WHM once the other one has been used.
The reason for all party members too have a reraise potion is..
If on the encounter with the last enemy you die, but your party manages too kill him off, then you wont receive your key item. Have the party member who are alive tell you when its about too die then raise yourself and stay clear of the action till it is dead.
Ethers HI-Ethers and anything higher are extremely important for mages, so are potions and higher for melee.
The most effective way too kill the boss is too have the SMN use the 3 2h method, effectivly useing yag drinks and ethers allows a SMN too pull off there 2h 3 times draining a huge amount of the enemies MP, multiple SMN are therefor extremely effective. the SMN can also cure the tank consderably before activating there 2h.
A THF with high marksman or archery skill is also useful, when it comes too the final boss when teamed up with a paladin,
The THF will be the first too enter the room and grab hate, when on low HP the THF should 2h, once worn out the PLD should then provoke and take hate, the WHM and SMN(if possible) should cure the paladin for as long as possible but if the pld gets too low on HP of loses hate he/she should 2h and take it back.
Many different party will have better results but this is the one that was succeful for me.
Hope it helps