If youre already familiar with competitive card games, consider choosing your colors based on the strategy type that best fits your personal style
If we can keep Teferi off the board, Didn't Say Please and Thought Collapse allow us to play a weird control-mill game, where we try to stick a copy or two of Drowned Secrets, always leave up a counterspell for whatever threat our opponent might have (while hopefully using the rest of our mana to cast cheap mill cards during our turn), and slowly mill away our opponent's library as we counter their threats
To be viable in Modern, a card typically needs to be cheap and efficient or offer unique utility, since the format is fast-paced and highly competitive
With Infiltrate you can do just that by gaining control of an opponents minion
Each token must attack the opponent it's associated with if able
Phyrexian Dreadnought ($278) Phyrexian Dreadnought has a very real drawback, so it's not something to just jam in a deck because any deck can cast it