This is a community deck list submitted by Nathan.
Imagine you're at FNM. You've got your pet deck, advisor tribal, and you're smugly shuffling your deck. You haven't tested it at all, but you know it's going to thrash whoever dares play against it. Just thinking about the brutal combination of power trapped within you deck gives you chills.
Then you see your opponent. There's nothing assuming about them at first. They've got a nice backpack, a clean playmat, and a plain deckbox. They shake your hand and you can hardly hold back your gleeful laughter at their impeding defeat.
That is, until they pull it out.
It's huge. You've never seen anything like it. A die, twice the size of your head and almost as dense. It's metal with gleaming, clear numbers on each side. The table buckles under its weight when they set it down. And in that moment, you realize the match is over, because someone with a die like that can only be playing one deck: I Think We are Going to Need a Bigger Die.
Adapt is the name of the game here. We've got 101 ways to put counters on our creatures and even a few payoffs other than simply bigger, scarier creatures.
Personally, I've been looking for an adapt deck for a while. I know that mechanics typically don't show their full strength on the set they're released in and grow stronger as more synergies enter Standard, but adapt had so many cool payoffs that I wanted to try it out regardless.
Quick note before I go any further: with War of the Spark bringing in a plethora of proliferate effects, adapt cards could become truly crazy. Keep your eye out for good adapt lists because I'm sure someone's going to come up with one. Maybe most of it is already in this list!
The most powerful part of adapt, I believe, is the ability to add counters to our creatures without using a card to do so. Nathan understood this when building this list and focused not on casting spells that add counters, but rather creatures that either made use of counters or could also add counters without spending a card on it. Shalai, Voice of Plenty is a great example of this.
What this allows us to do is play our creatures out normally as if we were a typical midrange deck, then when we're at a decision point, we can take the action that benefits us most. Is our opponent on control and looking to boardwipe? Then we'll grow our creatures and force them to get minimal value. Are they aggro and looking to overwhelm? Then we'll either trade up on meet their swarm with our own. Is the board at a stall? Then we can pump mana into our creatures for value. If we loaded the deck with cards that just put more +1/+1 counters on our creatures, then we don't get that kind of choice. We're locked into the aggro plan.
But what's that? 2 copies of Hadana's Climb? Oh no, my logic is foiled!
Actually, here Hadana's Climb is perfect. It's not just a spell that puts counters on our creatures, it's a payoff that can straight up win the game in a single turn. If we play it on curve, it can start building our smaller guys up for free, and if we play it late, it might just flip and activate on the same turn for lethal flying damage. I'm really glad to see it in this list.
Hydroid Krasis probably doesn't need any explaining here. He's a great payoff for the ramp with Llanowar Elves and Growth Spiral, plus he enters with plenty of +1/+1 counters which synergizes with the rest of our deck.
I also want to mention how well Frilled Mystic works with our gameplan. We've got a ton of activated abilities on creatures that we can hold up until our opponent's end step and all these abilities are pretty good, so we're usually happy even if that's the only thing we do with our mana. If our opponent does happen to cast something we do care about, we can forgo activating the ability to counter it with Mystic.
Right off the bat I'm gonna say: I've never played with Hadana's Climb, but holy Snickers it is fun. It's always been a card that I haven't quite been able to play, either because I haven't found the right deck or I didn't think it was strong enough. Let me tell you now, it's pretty good. And not just good: fun.
Unfortunately, I wasn't able to get a good variety of decks to play against. It was pretty much all either green/black+splash color, mono red, or an experimental deck with cards from War of the Spark. That being said, I was able to get a pretty good read of what was good against those decks and what kind of floundered.
First: the adapt package of Biomancer's Familiar plus any adapt abilities was generally a little too "cute". That is, trying to set it up and execute it to where I would gain a significant advantage rarely worked out. Either one of the creatures would get removed, or my opponent would just attack over me for the win. The reduction on Biogenic Ooze's ability didn't often come into play. I will say, however, that the reduction on Shalai's ability was pretty nice on the few times it did matter.
Second: Biogenic Ooze is crazy. He's pretty vulnerable the turn he comes down, but if he survives at all, he soon becomes unmanageable for the opponent. 2/2s that require no card investment and passively grow are fantastic at any point of the game. Getting an Ooze down and protecting him with Frilled Mystic felt great.
Third: As much as I love the card, Resplendent Angel doesn't have any synergies in this deck. Yes, it's strong, but 1) we don't have any other way to gain 5 life—Krasis for 10 only happens when we've already won—and 2) getting triple-white to activate it is extraordinarily rare.
Overall, I won most of my matches. The creatures in this deck tended to outgrow and out-smash creatures in the aggro decks I faced while also offering some great value.
I think there's a lot of great things going on in this deck and a few tweaks could really help it to shine. The first thing I'd do is drop the Resplendent Angels for the reasons I just mentioned up above. I would also probably drop the ramp, at least the Llanowar Elves. Those are best when we have strong turn 3 plays, but we have a ton of things we want to be doing on turn 2: Growth Spiral, Incubation Druid, Biomancer's Familiar, and Growth-Chamber Guardian.
As for additions in their place, I'd probably add some interaction like Conclave Tribunal and increase our consistency by bumping Ooze to 4 copies and Shalai to 3. You could also consider some counters, though those would mostly sit in the sideboard. Increasing Frilled Mystic to 4 copies is probably fine as well, though you may have to lower the curve elsewhere.
That's a wrap on "I Think We are Going to Need a Bigger Die." It was a fun experience and I'm excited about what sort of Simic decks we'll see with the new set. Until then, don't forget your 20-lb mammoth die, because for this deck, you just might need them.