Varolz and savageborn

[Taysby]

How would this combo work
{Varolz, the scar striped} and {savageborn hydra}
Would you be able to chose the hydra's mana cost because of x?
Varolz doesn't ask for cmc, it just asks for mana cost.

[Keyeto]

X would equal 0 in this case. Unfortunately, you'd pay 2 mana for a 0 power boost.

Here's the relevant ruling on Varolz, from Gatherer:

4/15/2013 If the creature card you scavenge has {X} in its mana cost, X is 0.

RESOLVED