Path of Exile: Ultimate Party Buffs?

Path of Exile is a game that can be played in a group of up to 6 players and has a massive number of different options for how one character can do things to help the other characters in their party. Group buffs, enemy debuffs, specialized roles... The world is your grouping oyster!

And yet right now I feel like I get very little benefit from playing with my friends right now. We've all built characters in order to be able to successfully play alone which means they're all self sufficient. They haven't really put any effort into buffing a group (since it tends to be more expensive skill point wise to buff a group than to just find something to buff yourself) and the efforts put into debuffing the enemies will often come into conflict with each other (curses overwriting each other, elemental equilibriuming away an ally's damage, knockbacks, non-magic finders killing things).

So we started mulling over the idea of creating characters actively designed to work well together. If a character is built knowing they're going to get buffs from friends then they can make tradeoffs as they build their character. For example, if I know someone is going to make some really good curses to put on the enemy then I know I don't have to put any skill points into making my curses better. I don't have to waste skill gems on a curse setup. If I know someone is going to focus on doing a lot of damage then I don't have to worry about taking any damage nodes in the tree at all! Everyone can focus on being tough and doing a couple of good things for the group and actually play together without feeling bad about it.

I'm a little hyped, but now I want to make sure I pick up all the ways to help that I can! So I wanted to go through the list of skills and uniques and stuff to see what the different ways of helping out would be. It's important to not try to take too many helping things and end up squishy but it's entirely possible there are some fairly trivial buffs that people could pick up as long as they know about them. So I want to have a list of broad 'roles' and then a list of extra add-ons that could be picked up.

Roles:
- AoE damage dealer
- single target damage dealer (for bosses)
- aurabot(s)
- multi-curser
- magic finder
- super tank

Specifics:
- elemental equilibrium (would need to coordinate to use the right element)
- conduit to share power, frenzy, and/or endurance charges
- consecrated ground
- no stun after blocking from Guardian
- speed buff after warcry from Guardian
- armour, energy shield, physical reduction, life regen from Guardian auras
- attack/cast speed, damage, resists from Necro auras
- maim
- blind
- culling strike (@20% from Slayer)
- taunts (double reduction from Champion)
- damage and move speed from Champion
- bleeds buff Bloodlust support gem
- knockback (reverse with unique gloves?)
- stuns/freezes
- hinder
- warcries?
- corpse consumption?
- vaal auras
- frost bomb (cold resist reduction)
- spirited response jewel (rallying cry -> mana regen for party)
- the vigil jewel (vigilant strike fortifies the party)
- dying breath weapon (curse, aura, damage amp) {animate guardian?}
- shaper's seed amulet (health/mana regen aura)
- leer cast hat (damage amp) {animate guardian?}


Enemy damage increases
- Inquisitor (nearby 16% elemental damage)
- Champion (taunted 20% damage)
- intimidate (Champion)
- Warchief (near totem 16% phys/fire damage)
- maim support gem (10-14% physical damage)
- shocks!
- wither (140% chaos damage)