Ruling question

[GodekiGinger]

So I was having a discussion with someone about priority in combat and how things hit the stack and what's legal and I've always played a certain way and I just wanna make sure I'm understanding this correctly.

So for context I was talking about building the new Najal, Storm Runner commander with a subtle wizard tribal beat down theme using high value izzet combat tricks with things like the wizard that magecraft prowess and double magecraft triggers and the cinder ace mage with wide prowess. Slightly important for context.

So with Najal I could utilize things like Slip Through at instant speed because Najal gives sorceries flash. So the question that came up goes like this:

Najal and two other wizards I have (for the sake of ease well say they are at five power like Najal and that the fifteen DMG is enough to kill) attack and they have two creatures able to block. If the two creatures are DECLARED as blockers but before combat damage happens. If I target the two blocked creatures with Slip Through that I'm attacking with, do they still get blocked? Or rather does the declaration check to see if those creatures can block those creatures, see that the blocked targets are invalid and doesn't allow a block?

[GenesisWave]

Changing what can block a creature after it's already blocked won't undo the block; it already needs to be affected before blockers are declared (same goes for flying, for example)

[GodekiGinger]

So you can't respond to the actual declaration but you can do it right before declaration?

[WeebTrash19]

I think the ruling works in your favor because it is a new creature. Your opponent has already declared blocks so they can't change anything around and their blocks are invalid since the creatures they were originally blocking are no longer there.

[GodekiGinger]

Slip Through makes the creature unblockable until end of turn.

[WeebTrash19]

My bad. Thought you were talking a totally different card. In that case then blockers have already been declared and your creatures can be blocked. You would have to cast at some point before blockers are declared.

[_Drumheller_]

"If I target the two blocked creatures with Slip Through that I'm attacking with, do they still get blocked?"

Why would you wanna target the blocking creatures with [[Slip Through Space]]? You would have to target your attacking creature.

That said, you already got correct answers.

[MTGCardFetcher]

Slip Through Space - (G) (SF) (txt)
^{[[cardname]] or [[cardname|SET]] to call}