Play a card for no mana cost and X.

[xTrainx]

So lets say I have a card that allows me to play a card without using its mana cost.

This could be cascade, it could be Memory Plunder, whatever.

So lets say I decide to Memory Plunder a Blaze. What should the value assigned to X be?
What if I cascade out a blaze. What should x be?

[Paradigm Shift]

X will be 0.

[cdr]

X: Many cards use the letter X as a placeholder for a number that needs to be determined. All instances of X on an object have the same value. If a spell or activated ability has a cost with an "{X}" in it, and the value of X isn't defined by the text of that spell or ability, the controller of that spell or ability chooses and announces the value of X as part of playing the spell or ability. (See rule 409, "Playing Spells and Activated Abilities.") While the spell or ability is on the stack, the {X} in its mana cost equals the announced value. If you're playing a spell that has {X} in its mana cost, the value of X isn't defined by the text of that spell, and an effect lets you play that spell without paying any cost that includes X, then the only legal choice for X is 0.