Mental Misstep

Each Phyrexian mana symbol in a spell's mana cost contributes 1 to that spell's mana value. For example, Mental Misstep's mana value is 1, regardless of how its cost was paid.

To calculate the mana value of a card with Phyrexian mana symbols in its cost, count each Phyrexian mana symbol as 1.

If a spell has {X} in its mana cost, X is considered to be the value chosen for it while that spell is on the stack.