Pugna - Hardlane to Hell 6.85

Nether Ward does not burn "mana by 1.5/3.0/4.5/6 x amount of mana used" but has an aura that provides negative mana regeneration to ennemy heroes in a 1600 range.

The regen is important but secondary to health and mana pool. Spells don't de-activate Tranquil Boots, only right click, so you get the full regen from it as long as you don't take damage. The ultimate can be cancelled by tapping R and also by getting out of range. Force Staff provides 4hp/s regen and Linken's Sphere provides 6hp/s regen too. That totals 32 hp/s regen! Obviously not enough to be able to support 300hp/s drain. The main thing you need to be able to do is to sustain the drain with your health pool - Dagon helps a lot in this respect with the strength buff, as does Black King Bar and Scythe of Vyse. Necronomicon could be a good item too. I'll update the build later.

Remember though that with an Aghanim's upgrade, your drain cooldown is 0. So you can drain into your carry and then drain the enemy :)

Another thing you have to remember is magic resistance. This is also factored into the equation. Not a good idea to try and life drain a heavily fed Pudge.

When spells are cast it does damage 1/1.25/1.5/1.75 x the amount of mana used for the spell plus 1.5/3.0/4.5/6 x amount of mana used also burned. It will effectively punish heroes that have spell toggles with double mana drain and can kill any hero with high magic damage burst (Lion, Lina etc...).

I've never played a Pugna in my life, but I do have a theorycraft question. Since your ulti transfers 300 hp/sec and since Pugna is pretty squishy, wouldn't you need some serious HP itemization for that to be much use, especially after Aghs? Or is it always used for 3-4 sec max in practice and if that's not enough you're already dead?