When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
Hydroid Krasis enters with X +1/+1 counters on it.
Hydroid Krasis's first ability triggers as you cast it, and that ability resolves before the spell itself. It resolves even if Hydroid Krasis is countered.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.