Since its effect has no specific way to mitigate your opponents using its gifted resources against you, youll have to constantly justify to them why they ought not attack you
Primarily sticking to blue, black, and green cards, plus one red outlier, these can slot into a wide variety of situations and decks, generally with very little setup needed to play them other than getting past a few turns and casting a healthy number of spells
Make the cards look nice and clean.
Kiki-Jiki, Mirror Breaker + Seeker of Skybreak / Deceiver Exarch A simple, yet effective combo that lets you create an infinite number of creatures to finish your opponent
You can go far by just focusing on things like balance, mana curve, and card advantage