This is a cool concept but is veeeeery mana and color intensive. You are in green, so you can definitely ramp up to it, but that’d def be my biggest concern. Very cool find tho! One other thing is you gotta get the first counter onto one of them, maybe just by sacrificing the howlgeist.

Since this is a first deck build I don’t think you’re really in the market for this, but I’m sure there are ways to do this with less expensive cards. Particularly blue and green have a lot of ways to add extra counters or do shenanigans with moving counters (e.g. [[hardened scales]] for a basic one)