As a 2/3 for 2, Winding Constrictor’s stats are solid enough for Standard play—it stays at least even with basically every 1- and 2-drop that is currently played. Sylvan Advocate is a 2/3 for 2 that doesn’t see much play right now, so clearly we need more than just the body.
There are many cool things to do with Winding Constrictor—you can increase charge counters, energy counters, or you can even donate it to them and increase poison counters. The main use for the ability, however, has got to be increasing the number of +1/+1 counters on your creatures.
A while ago, I played a G/W Hardened Scales deck to the Top 16 of a GP that revolved around exactly this mechanic. While I didn’t really like the deck, it’s undeniable that its great starts were just busted, and it was the bad draws I could live without.
Winding Constrictor is a Hardened Scales on legs. It doesn’t offer the super busted starts Hardened Scales did since it costs twice as much, but its good starts are good enough, and being a creature makes it a much more powerful card. One of the main problems with Hardened Scales was that you wanted to play all those creature enhancers and sometimes you just ran out of creatures, and Winding Constrictor makes it less likely that it will happen.
Winding Constrictor pushes you into B/G, but without Abzan Falconer there’s no real reason to be white anyway. You also lose Avatar of the Resolute, which was an amazing card in the deck, but you gain quite a few new tools, most of which will make the deck slower but more resilient.
The first of those tools is Rishkar, Peema Renegade.
A 3/3 Elf by itself, Rishkar curves perfectly into Winding Constrictor, giving you two 4-power creatures by turn 3, both of which can add mana if you want them to. Rishkar is legendary, but if it dies you just cast it as a Travel Preparations, so it’s not too bad.
The second is Verdurous Gearhulk.
At 8/8 you’re getting a ton of stats out of this card already, but add a Winding Constrictor and you can get up to 12 extra power. A curve of Winding Constrictor into Rishkar into Gearhulk puts them at 9 life and leaves you with 19 power in play split among 3 gigantic creatures (which would be a lot more impressive if people couldn’t play Emrakul on turn 4, but is still quite impressive). Gearhulk is also quite good with Rishkar’s Expertise.
The third is Drana.
Drana was lauded as broken at first, but hasn’t seen any play—still, it’s actually a very powerful card in the right shell, and Winding Constrictor is definitely the right shell.
The biggest hurdle in building this deck is in deciding which 2-drops to play. You want Constrictor for sure, but past that, you can play Grim Flayer (which is very good with pump spells to get it through), you can play Sylvan Advocate (vigilance is great with Rishkar), you can play Scrapheap Scrounger (comes back and makes sure you always have something to pump), you can play Smuggler’s Copter (duh) or you can play Gifted Aetherborn (lifelink + pump effects!). You can even play Longtusk Cub, since you get 1 extra energy when you connect as well, and an extra +1/+1 when you pump.
My inclination is that Smuggler’s Copter is actually the worst of the good cards, since you want to have big creatures and big creatures are bad to crew, but it’s such a powerful card that I could easily be wrong.
The second question is whether you want any 1-drops. All the 1-drops in G/B are kind of bad right now, but there are a ton of semi-decent choices: Gnarlwood Dryad, Loam Dryad, and Endless One seem to be the best. Normally I wouldn’t play any of those cards, but I think when you have effects that pump your whole team (such as Drana or Nissa), then having a 1-drop in play adds a lot of value. If you play Dryad, you probably also want Grim Flayer and some ways to put extra types in the graveyard, such as Implement of Ferocity. It’s really too bad you don’t have Thraben Inspector.
Here’s how I’d start:
This deck is really bad at turning Grim Flayer on, but it’s still a pretty good card even if it’s just a trampler that gives you some deck selection. It’s possible that Advocate is better though, since it protects your Nissa and also works better with Rishkar.