The biggest trick is not individual card design but making sure you have the right mix of cards (both in effects and costs) to get the job done
He is great against control, one of your best cards in that matchup
Heres the most impactful reasons to play an ally strategy
Minsc & Boo, Timeless Heroes Our penultimate planeswalker is this 3 loyalty Gruul option, and it's a lot of fun, it comes with a 1/1 Hamster with haste and trample to block attacks on it, and then you make another each of your upkeeps if it's not on the battlefield, to keep on blocking
Core mechanics for blues include card draw and card selection to keep options open
Creature - Wurm Creature (CTRL to add secondary) Draw Grothama, All-Devouring Other creatures have "Whenever this creature attacks, you may have it fight Grothama, All-Devouring." When Grothama leaves the battlefield, each player draws cards equal to the amount of damage dealt to Grothama this turn by sources they controlled