If you follow coverage, and more specifically, if you followed the GP in Houston this weekend (which you should have and you’re missing out if you didn’t!), then you saw that the GW Hardened Scales deck was all the rage. There were many top professionals playing it, players from many teams on it, and there were a ton of Hardened Scales mirrors in the feature match area.
The deck centers around, you guessed it, the card Hardened Scales. Without the Scales, the deck is still functional, albeit mediocre. With it, all of the creatures become much more exciting. Servant of the Scales transforms from a 1/1 with quasi-modular into a 2/2 that can add 3 counters elsewhere (or more, depending). Endless One can also come down as a 1-drop, or get an extra counter later in the game.
Avatar of the Resolute is one of the workhorse creatures, threatening to come down as a 4/3 trampler on turn 2 with the help of any 1-drop creature, and potentially much larger even a turn later. The other heavy lifter is Managorger Hydra. Hydra can already become a massive trampler, but with the help of Hardened Scales, gains multiple counters for every spell cast. Having cards like Endless One and Hangarback Walker in your deck also presents the option to pay 0 mana, discard one of these cards, and give your Hydra multiple counters.
Speaking of Hangarback Walker, it comes down with an extra counter, and every time you pump it with a Hardened Scales in play, you also get an additional counter there. The same is true for Abzan Falconer, who grants flying to all your creatures with counters on them, which is conveniently all of them.
The card that put this deck back on the map and made it a force is Nissa, Voice of Zendikar. Without Nissa, this deck is just too clunky and inconsistent to be a real factor, but Nissa is what makes it all exciting. She can create an army by herself, but adding a +1/+1 counter to your entire team, potentially several times, is amazing. The combination with Hardened Scales is too much for many foes to compete with.