Made it to 42:00 i think once, wasn't checking.
This is my Dream Team:

[Position 1: Ranged Carry]
You need one to kill the most fiery bosses, for example the golem, since melee attackers struggle a lot due to the passive. If possible, early game she focuses on dps, so the team has an easier time against bosses and spends more time on farming. It requires some supports to help if necessary. Arc warden can be deadly, his ultimate can be devastating in many scenarios. I would go for Clinkz, since he can transition very well to Ice Cream Hunter in the late game ( killing anfient aparition is a full time job. Someone's gotta sacrifice and he has a good set of skills to do it.
Moonshards, Wasp, Travels(for AA) or Agility Boots, King Rapier, Satanic, Dragon Javelin 5, situational item depending on hero and situations. An heart for rapid regeneration during travel times is nice, but optional.

[Position 2: Melee Carry]
There must always be one to hold against the hard hitting bosses. My pick is Legion Commander: She's a worthy carry, if you manage to carry her early game she can build midas and refresher for maximum gold and damage. Not a smart choice in ultra if you don't have a good team, since Legion will be terribly weak for the most important part of the game.
Moonshards, Wasp, Heart, Strenght boots, King Rapier for true strike, Refresher to scale incredibly ( 116 damage every 60 seconds after lvl 25 ), Battlefury 2 to clear. Should have an Heaven's Halberd in the backpack in dire situations to swap with Refresher.

[Position 3: Offtank/Allrounder]
You can skip this in 4p. The best in this position is definitely Phantom Lancer. His illusions will block any foe, aside for strong bosses. He will never solo a game but he surely will make holding back the horde very easy. His illusions gain the moonshard atk speed thanks to 7.00. Moonshards, Wasp, King Rapier, Heart, Manta, Diffusal Blade for the insane damage to the illusions and Agi boots is my build choice.

[Position 4: Aura Overlord]
A good player knows the value of an aura in a teamfight. Having a player dedicated to building auras will make every teamfight an easy feat. The best for this job is beastmaster, having innate auras both on him and his pets. Stacking even more auras will make any nearby ally a machine gun of mayhem. Any support who is very useful with just his abilities and doesn't need many items can take on this job ( es. Winter wyvern or pugna ). The best auras to get are Shiva's armaments, Vladimir Cuirass followed by Greaves Boots, Radiance, Pipe of Insight and Crimson Guard. Try not to overlap similar auras, since effects won't stack.

[Position 5: Roaming Support]
A selfless player, whose job is to help out lanes early and purchase those op tower upgrades no one buys. I really like Alchemist in this role, since with just a battlefury, boots and a few tp he has both the sustain and mobility to move around the map, clearing jungle camps along the way, earning bonus gold for tower upgrades and a few clarities or salves for his teammates along the way. The ultimate supporter gift remains the almighty " Giff Aghs". Playing this role leaves you gold hungry, and Alchemist can farm extremely fast in late game, transitioning in a few minutes to another Offtank/carry with an insane 0.10 attack speed with max moonshards and ultimate up.

Originally posted by SymphonicMetal:

[Position 4: Aura Overlord]
A good player knows the value of an aura in a teamfight. Having a player dedicated to building auras will make every teamfight an easy feat. The best for this job is beastmaster, having innate auras both on him and his pets. Stacking even more auras will make any nearby ally a machine gun of mayhem. Any support who is very useful with just his abilities and doesn't need many items can take on this job ( es. Winter wyvern or pugna ). The best auras to get are Shiva's armaments, Vladimir Cuirass followed by Greaves Boots, Radiance, Pipe of Insight and Crimson Guard. Try not to overlap similar auras, since effects won't stack.

Good one! A few tips, if you don't mind ;)

Items\auras that do stack:
For the starting phase:
Dominator + Vladmir's Offering + Headdress.
Multiple Orbs of Venom, Skadis, also when mixing them with each other.(Skadi slow wont stack with itself, but will stack with Orb of Venom. If you rely on kiting enemy creeps, you might consider picking Orb after Skadi).
Javelin's 85 magic damage stacks with MKB's 160 proc chance, and those two also stack with King Rapier's proc chance, so you have a chance to proc up to 160+160+85 bonus damage per hit.

For the mid-late phase:
Vladmir's Cuirass + Vladmir's offering and Assault Cuirass.
Shiva's Armament +Shiva's Guard(They also have 2 different cooldowns, so you can spam their active).
Solar Crest +Medalion of Courage(Also stacks when applied on enemy unit).
Desolator 1 + Desolator 2 + Blight Stone(but only when applied by 2 different attackers, e.g. Lone Druid and his Bear).

Tip of a day:
- Consider buying your carry a Perserverance, as its a shareable item(teammates benefit from wearing it in their inventories). Two Perserverances can almost nullify the mana problem on low manacost non-int heroes, as well as giving some damage and heal.

Heroes like Zeus, Doom, Winter Wyvern or Enigma, can replace a boss hunter hero completely.

Time: 46:00
Difficulty: Hard

Thanks to Enigma and Centaur, we survived alot.

Tip 1: Two kinds Shivas is a must.
Tip 2: Get Oppressor\Dominator. During the Ultra late wave, you can dominate a creep with good auras.

We should form a team of veterans and try to set a VERY high score!

48th minute of pretty easy last standing.
IO, OmniKnight, Windrunner, Timbersaw, Pudge.

62th minute on Normal.
Luna, Legion Commander, Drow ranger, Medusa, Nature's Prophet.

We've got overrun by bashes, cause creeps had super attack speed. They just plastered our faces against the ancient everytime. Slows are sick, I had moments where I die because I couldn't move fast enough(up to 100 movespeed...).

End game item build: 2 King rapiers, Daedalus, Boots of Agility, Satanic, Vladmir's Cuirass.

62 minutes once again.
Easy, 4p game.
Earth Spirit, Invoker, Viper, Arc Warden.

The moments I regret not picking Pudge, kinda. Being more magic resistant and having tons of health might've been actually helpful.. except Earth Spirit has this neat rolling skill that is independent of my 100 movement speed, so I can avoid getting rounded by creeps.

At first, Shiva combo helped me tanking, but then, once every creep had like up to +7 bonus skills, mostly of pure/magic nature, they've started rolling my face down. Bosses with Spectre's Dispersion hurt like a ♥♥♥♥♥! Killing one Dispersion having boss drains around 45% of the heroes health around it, it actually negates health regen and lifesteal, leaving you half a health. Squishy hero with crits can actually instakill him\herself, and help everyone around die faster, with just one good crit.

Items: Shiva's Armament, Shiva's Guard, Heart of Tarrasque, Eye of Skadi, Pipe of Insight, Brilliant Radiance.

75 minutes last stand.
Axe, Invoker, Phantom Lancer, Clinkz, Phoenix(left at ~50 minutes).

For Clinkz: 3 King rapiers, Dragon lance 5, Vladmir's cuirass, Satanic.

Clinkz deals some sick damage if he eats a fire golem or a dragon. I was dealing over 2k damage per hit.

During the late phase, creep's movespeed and attack speed is so fast, they'll kill you in 2 seconds of stun.

77:30 on 5p mode with 4 players ez difficulty