Throne of Eldraine spoilers started this past week and the set is definitely turning out to be interesting, to say the least. The first thing we should cover is the new mechanics which can be seen in the following cards spoiled so far.

Food Tokens

The Food token creation is a very thematic addition to the set. The fact that you have to pay 2 mana and sacrifice it to gain 3 life makes it look like more of a "worse" clue token, as most players would rather draw a card than gain 3 life. The one benefit is that because gaining 3 life is much less powerful than drawing cards, it is possible for WoTC to push the mechanic more on cards. These tokens are artifacts, so there is potential synergy with previous artifact-based strategies like Affinity.

Potential Speculation Opportunities

Currently, I don't see any speculation opportunities for this mechanic at this time. We haven't seen any spells creating Food tokens that create a lot of tokens for cheap, which is what would likely play well with older artifact strategies.

Adventure

This mechanic is a bit more interesting and more complicated than the Food tokens. You can either cast the Adventure part of the card and then exile the creature part, after which you are allowed to cast the creature part from that exiled zone, but ONLY if it was exiled with the Adventure mechanic. This may be a bit of a nightmare for judges who have to differentiate between the card being exiled in this manner versus any other.

That being said, it's similar to the Flashback and Aftermath mechanics in that it allows you flexibility with your spells after they've been cast. With those two mechanics, we typically see the original spell being a bit over-costed for this flexibility.

We have seen a fair number of these cards spoiled so far and while nothing comes off as heavily pushed, I personally see some benefits to Embereth Shieldbreaker as a sort of Wear//Tear style sideboard option. It gives you the ability to take out a problematic artifact early and then serve as an additional threat later in the game when resources have been used up. This mechanic has great potential if any of the cards are pushed in power level.

Potential Speculation Opportunities

While I haven't seen anything with the Adventure mechanic that combos with anything in eternal formats, it is important to note that there are some fairly aggressively costed creatures that happen to be Knights and have this mechanic. With enough support, it is very possible we could have a Mardu Knight aggro deck in Standard. We are already seeing some movement in older Knight creatures for Commander with Knight Exemplar and Kinsbaile Cavalier trending upward.

A Knight that I think has a LOT of potential in a Mardu Knights Commander deck is Marton Stromgald which is a Reserved List card that provides a repeatable powerful pump effect for aggro decks. I've previously built a Commander deck with him as the Commander, enabling the deck to kill multiple opponents out of nowhere thanks in large part to him as the general.

Another potential speculation target for a Mardu Knights Commander deck is Eastern Paladin, specifically 8th Edition foils. Green is the most powerful color in Commander, so it's likely to have plenty of targets in most games. At present, the 8th Edition foil is the only foil available with the original artwork from Urza's Saga, and you can pick them up for under $2. You could also go for the 7th Edition foils, as those are still around $8 and have unique artwork.

Adamant

This mechanic is similar to Devotion from Theros block in that it incentivizes players to not be too greedy with their mana bases. We haven't seen a ton of cards spoiled with this mechanic yet, but the few that we already have appear to be over costed in their non-Adamant abilities and simply 'okay' with Adamant. It is important to keep in mind that Devotion was pushed hard in Theros and spawned multiple tier 1 Standard decks: Mono-Black, Mono-Blue, Mono-Red, and Mono-Green devotion. This type of mechanic could be powerful if WoTC pushes it. It's also important to note that WoTC released the set schedule for the upcoming year and the next block appears to be a return to Theros.

If we see a return of the Devotion mechanic, it's likely we will see some of the Adamant spells played in those decks.

Potential Speculation Opportunities

As this mechanic is based on the mana one puts into the spell, it stands to reason that lands that can produce multiple mana of a single color might make for decent speculation targets. As we are returning to the plane of Theros, I might be hesitant to buy any more Nykthos, Shrine to Nyx pending a possible reprint in the set. I do like the Shadowmoor block filter lands as potential speculation opportunities. They provide mana fixing when needed but also serve as a way to increase a single color of mana.

Prior to their reprinting in Masters 25, many of these lands were $20+. I especially like the ones that were printed first in Eventide as that set was less opened than Shadowmoor and there are arguably fewer of them. Interestingly enough, there appears to be almost no difference between the original Eventide printings and the Masters 25 reprints. It may be wiser to target the Eventide copies if you decide to speculate on these.

Fetchable Spell Lands

While Witch's Cottage isn't absurdly broken, lands that have spell abilities are always something to keep an eye on. Even more important, just like the Shadowmoor cycle (Mistveil Plains, etc) this land can be fetched out, which is something to keep in mind. It's also important to note that the Shadowmoor cycle always came in tapped, which is definitely a deck-building cost, whereas this land can come in untapped later in the game.

Potential Speculation Opportunities

As we only have one of these lands currently spoiled, I wouldn't speculate on anything just yet. If we get one that is clearly pushed, picking up the cheapest fetches that can retrieve it wouldn't be a bad idea, especially given that the Khans of Tarkir fetchlands all currently look like reasonable pickups anyways.

Syr Konrad, the Grim

Finally, I'd like to close with a focus on this card. While this rules text isn't a mechanic we'll necessarily be seeing on more cards, when this card was spoiled I immediately went and bought up 13 nonfoil and 2 foil copies of Morality Shift as a potential combo card with Syr Konrad, the Grim. We have already seen some movement on Mortal Combat foils due to this card as well. The doctoral thesis comprised in his text box screams combo potential and the fact that his damage is to each opponent means it's easy to combo kill all opponents in one shot if you build the deck right. Keep your eyes peeled.