Sweet Unique Passives

These are four unique passives that seem ridiculously powerful, but never see much use. Thoughts?

http://paragon-game.com/wiki/cards/drink-the-spirits

This seems like a worse version of life steal to me, but it could be good for a squishy character like Twinblast to regain all of his health from killing Steel.

http://paragon-game.com/wiki/cards/necroveil

This card seems powerful for a ganker, but Kallari is the only corruption ganker and it's redundant for her.

http://paragon-game.com/wiki/cards/traitors-touch

This seems ridiculously powerful for killing tanks, but that's about it. Maybe it could be used as specific tech against Steel/Sevarog?

http://paragon-game.com/wiki/cards/infinity-stream

Maybe this card could be good with Gideon? This card seems like a one-stop shop for infinite mana.

http://paragon-game.com/wiki/cards/chieftains-crown

This seems ideal for a pusher. Imagine this with super minions!

http://paragon-game.com/wiki/cards/madspore-sash

http://paragon-game.com/wiki/cards/radiant-mantle

These both seem very powerful in team fights. Maybe a Muriel support build could use these both and get all of the AoE buffs? That could be very powerful and could easily allow you to just storm through and take the core.