Mechanics of Silence

If the other team pops their BKB's early; then it's still a win. Won't even have to throw the ulty. If they don't; then they won't be able to due to Disruptor Ult.

So it's a damned if you do. Damned if you don't scenario.

There are allsorts of odd cases with silences, magic immunity and what overrides what. Sometimes you need to know the specific matchup of powers to see what works over what. The general rule is that silences stop heroes from directly casting new abilities (not item actives), but doesn't tend to stop ones they've already used (unless they're channelled). Passives sometimes still work, but not in all cases.

For example, using Silence on a Bounty Hunter who has just used Wind Walk won't make him visible (the effect has already taken), but would work against a Riki. Strangely, Moonlight Shadow can be temporarily broken by using Silence on Mirana, even if she's already cast it.

There's allsorts of interactions with magic immunity too - for example spells like Enfeeble can't be cast on magic immune heroes (afaik), but their effect will still hold if they're cast and then the hero becomes magic immune. Generally spells that go through magic immunity like Reverse Polarity, Black Hole and Fiend's Grip do the disable effect, but the damage is blocked. There's even weird exceptions like Echo Slam where part of the damage goes through, but part of it is blocked.


Damage Types

What about Riki's cloud. I'm quite sure that's a mute. These days, that cloud is more annoying than his invis

Why would it be a mute? It just stops you from casting spells. You can still use force staff/blademail and passives exetera.
The slow and blind are just added effects that have nothing to do with mutes.
Aghanim disruptor ultimate is NOT a mute, its just a silence that stops items.
Mutes stop passives like lifesteal evasion crit and all that stuff.
There are only 2 mutes. Doom and Duel

http://dota2.gamepedia.com/Silence