It that betrays would be better because all you have to do is make them sac and you automatically get it. Attacking isn't really necessary. For this deck however I would encourage you to add
scourge of skola vale. This way you can sacrifice the creatures you just took control of from your opponent and grow your hydra even more. Also if you add
dowsing shaman to the deck combo with cards like
mind control or
illusory gains then you'll constantly
deprive your opponent of creatures. Add
glint for extra protection for your creatures and you're good to go. (personally I'd add black to make the opponent SACRIFICE permanents) but if you're running kruphix then you're gonna want to go for mana production, hand advantage, and to an extent control.