Mental misstep and gaddock teeg

[John Cox]

Just clarifying, I can pay the 2 life portion of the phyrexian mana symbol to cast Mental misstep with gaddock teeg out right?

[hyc8028]

Of course.

Noncreature spells with converted mana cost 4 or greater can't be cast.

Noncreature spells with {X} in their mana costs can't be cast.

MM is none of that.