Yeah, I think just a vial and 1 card is kind of weak when crafting is about mixing cards to create other cards. So your suggestion of Vial + 2 cards (1 out-element and 1 in-element) seems okay.
Vial + …
Lightning + Protect Artifact= Quintessence
Shockwave + RoF= UG
Drain Life + Chaos Seed = Liquid Shadow
Plague + Twin Universe= Aflatoxin
Plate Armor + Freeze = Basilisk Blood
Pandemonium + Heal = Antimatter
Fire Bolt + Blessing = Rage Potion
Gravity Pull + Nova = Black Hole
Heal + Momentum = Adrenaline
Holy Light + Thunderstorm? = Luciferin
Sundial + Momentum = Precognition
Freeze + Mutation = Nymph's Tears