Stay safe, wash your hands, and keep fighting the good fight
Assuming you can regularly hit cards with it, Gilgamesh looks very powerful, but completely unusable outside of that
Building The Deck Zack Fairs ability to pass on counters is limited by the fact that he has to die to do so, and a single +1/+1 counter isnt valuable enough to deal with the growing commander tax as you loop casting and sacrificing him
Keep in mind your character needs to be lacking evasive, or the trick can't get you around the blockage
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of The Water Crystal's first ability)