The value of X is calculated only once, as Heidegger's first ability resolves
Gitaxian Probe You may think that [c]Gitaxian Probe[/c] costs one mana, but in the vast majority of circumstances, youll want to play it for zero mana and pay the two life instead
Arcane Denial is easy to cast, replaces itself and gives the opponent a consolation prize
In the late game, being able to put a counterspell back on the top of our deck to use the next turn is nice, and getting back Into the Story to draw four more cards is a great deal
(...) [Pokmon products] built up the buzz before the movie release opened the floodgates." "Burger King latches on to Pokemon craze with six-week movie promotion"
Paying six mana for that effect is atrocious, but Soul Spike has an alternate casting cost - you can exile two black cards from your hand instead of paying its mana cost