First, the deck features a number of incredibly strong creatures with powerful abilities, which serve as targets for your +1/+1 counters
Given that, the deck is built on a base of counterspells, bounce, and cheap red removal to make sure it can last until its ready to combo off
7 Metalwork Colossus Metalwork Colossus is an artifact payoff that can hit the battlefield for little to no mana, so long as you're running a healthy number of non-creature artifacts
Many characters of this Ink color offer the ability to heal damage from your other characters and will offer benefits like card draw when you do
Archmages Charm is extremely pushed, a solid permission spell, a good way to build card advantage for hitting land drops, and a fantastic tool against Deaths Shadow, Wild Nacatl, Goblin Guide, Pyxis of Pandemonium, Champion of the Parish, Aether Vial, Delver of Secrets, Hardened Scales, Amulet of Vigor, Benthic Biomancer, Glistener Elf, Noble Hierarch, Viscera Seer, and sometimes even Hexdrinker (just to mention a few)