So many decks play the pair of five-drop enchantments, and so I think this will be a solid drop
As long as you keep another creature or two and play some extra lands, the +1/+1 counter doubling goes nuts and makes the math really difficult to oppose in combat
The set will feature 165 cards before secret rares, so the Trainer cards, Energy, and secret rares haven't been revealed yet
You can also have up to 59 copies of each Basic Energy card, not counting non-foil energy cards without a collector number or expansion icon
With Equipment as your main strategy, the deck slows down a bit, trading explosive turns for a more toolboxy, resilient deck that has long staying power
Debuting in Commander 2015 on the card Broodbirth Viper, this ability allows the creature that hosts the ability to duplicate itself and attack each other player in your Commander pod