If these cards

[DeathAngel]

If I had brink of disaster, and I played it on my opponent's creature if I took control of it and tapped it would it die? And secondly if I played on an already tapped creature would it instantly die?

[Coffee Vampire]

{Brink of Disaster}

[Coffee Vampire]

a) yes it would die.
b) no it would not die. It only dies from becoming tapped; not from being in the state of already tapped.

[Kaleo42]

What if you tap an already tapped creature with brink on it? Like with frost titan or sleep

[JaxxLevia]

What if you tap an already tapped creature with brink on it? Like with frost titan or sleep

Once a permanent is tapped it can't be tapped again, since it already is in said state. You'll need it to untap before it can be tapped again.

[BlackJester]

Also, if you control it you need to have a reason to tap it, like attacking or using an ability. You can't just tap creatures for the sake of tapping them.