Orb Effects aka Unique Attack Modifiers. What Stacks What doesn't?

Someone please explain this to me :)

Eye of Skadi stacks with lifesteal.

Lifesteal doesn't stack with lifesteal.

Lifesteal doesn't stack with Desolator.

Mjollnir stacks with lifesteal, Desolator and Eye of Skadi, but when the effect triggers, the other orbs won't use their effect.

^Thank you for this.

Clarification:

Desolator and Eye of Skadi stack?

Lifesteal stacks with Eye of Skadi only on ranged heroes. On melee heroes, you can only have one or the other.

Actually,lifesteal stacks like this:Vladmirs Ofering+another lifesteal instance(ex Helm of the Dominator)

Or, Satanic stacks with Lifestealers Feast.Everything else stacks with Skeleton Kings Vampiric aura.(and by everything else I mean one instance of lifesteal like Satanic.Obviously if you get another orb effect it will work as hades said +the aura).

I'm not sure but I believe Maim also stacks with ranged skadi. I know bashes don't stack anymore(way back in the day troll warlord omfg!!!)

Basically also, things with a chance to trigger can overide other unique modifiers as long as they have the higher priority. It was like this in dota 1 so correct me if I am wrong for dota 2, but Desolator is the top priority followed by chain lightning, lifesteal, then Mana burn,bash,then maim,then slow. At least I think it is that order, if someone can confirm plz.

I think lifesteal has a higher priority than desolator, I remember once I tried MOM and Desolator and only MOM worked.

was this the static effect of lifesteal, or when you activated MoM did it stop deso?

Wrong. Try it for yourself. Granted, on melee heros Vlad's probably makes sense over another source of lifesteal by the time you have Skadi anyway, but nothing is wrong with having a support grab vlads and you grabbing a HoTD to go with your Skadi.

Hmm the item skadi says that it only stacks with lifesteal on ranged. I personnaly have not tried it in dota 2, but I know in dota 1 it does not. Perhaps it is bugged.