undermine counterspell rulings cast on spell cannot be countered magic

[Dude]

Can I cast undermine on a spell that cant be countered such as Combust? Will other player still lose 3 life?

[zehamberglar]

This is a hard ruling. One of two answers:

No. Undermine has to have a target to be cast, and it can't target a spell that can't be countered.

or

Yes, as it doesn't have protection from counters, it just can't be countered. The Undermine targets Combust, they lose 3 life, and combust resolves.

In my personal opinion, I think the fact that it can't be countered removes the ability for undermine to target it as it's not a legal target, but I can't give you a definite answer.

[Arix]

Undermine (and any counterspell) can target a spell that can't be countered. It's like targeting an indestructible artifact with Shatter - it's a legal target, it just won't do anything. And yes, the controller of the spell will lose 3 life even though the spell isn't countered.

[Dude]

what happens if I target a urza's rage with dissipate, and when urza's rage resolves its target is not legal so its countered, is it exiled or does it go to graveyard?

[Arix]

Always keep a card's Oracle text in mind. Dissipate says:

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

[Minineko]

Always keep a card's Oracle text in mind. Dissipate says:

In case you can't put 2 and 2 together, this means you can target Urza's Rage with Dissipate but it be able to counter or exile anything.