by Phantaskippy
Here's what I do when designing a new deck:A. Determine their role
1. What does your hero do primarily, are the turtles going to be damage, tanking, support, utility?
2. Look to an official hero deck that does similar at the power level you want, get an idea of how much damage, destruction, etc. they can have before being overpowered.
B. Design Mechanics
1. How will the hero play, are they a slow building late game crusher like AZ, a steady and sometimes bursty damage like Ranger, or a straight up damage dealer that does almost nothing else like Ra.
2. How will the deck function? Does it play fast and live off chains, look for big one shots or rely on using and maximizing powers?
C. Make it Special
1. What makes this deck different and cool?
For the Turtles my first thought is make each turtle function differently, you need to give the feeling that you have 4 unique characters in this deck. Doing that isn't easy.
To borrow from the Sentinels a bit, think about how the Signature cards work, and all their cards that any one of them deal damage.
With the Turtles you could have signature cards of their weapons that give different effects when they deal damage. Just off the top of my head something like:
Sai
Equipment/Signature
When Raphael deals a target damage reduce damage dealt by that target by 1 until the start of your next turn.
Then have their base powers reflect different roles on the team, like:
Donatello: Search your deck or trash for an equipment card and put it into play, shuffle the deck if you searched it.
Michealangelo: Deal 1 target 2 melee damage
Then come up with some ways to use additional powers, the sentinels have a way of doing it, you could also go for a straight use an additional power on your power phase or use one-shots like:
Team up card name!
One-Shot
One Turtle deals a target 2 melee damage
A different Turtle may use a power now.
The turtles obviously lend themselves to dealing damage, but I think a moderate damage + Utility role (destruction, reduction, etc.) would fit them perfectly.
You'd also want some ways of dealing non-melee damage, like maybe a donatello invention card that lets him choose from several types of damage, or something where Raph throws his sai's for projectile damage, just so immune to melee wouldn't crush them.