New MTG Mechanic Spotlight: Boast

Tom Anderson Strategy

Kaldheim spoiler season sure has given us an exciting start to 2021! New legends, new Gods, new modal double-faced cards, bearing all manner of powerful and unique effects. If anything, this candy-shop effect has left the actual mechanics of Kaldheim a bit lost in the shuffle! 

Boast and foretell are the latest in a string of very cool keywords WotC have come up with recently, and are worth examining in detail before we sit down to start seriously predicting and brewing for a post-Kaldheim meta. We’ll start with boast today, and break down foretell next week!


When I look at new mechanics, I try and see both how they generate synergy with what decks and mechanics are already doing at the moment, as well as what new ideas they might bring to the forefront. Boast ties a large part of your creature’s value into attacking, which feels like a relieving de-escalation from an environment where most playable cards get their value on ETB (or even earlier in the case of adventures!)

Even more interesting, the range of payoffs for boast are extremely open-ended, including all sorts of utility effects and other incentives not normally associated with attacking. This means that it can be effectively used to make decks care about combat which otherwise wouldn’t. This adds an extra tactical dimension to the game and, in turn, allows R&D to make boast cards quite powerful, since you have to “solve a puzzle” to use them. Combat is one of the most interactive and skill-testing parts of Magic, so I’m always happy to see WotC encourage it through mechanics like boast and monarch.

Another thing I appreciate about boast is that forcing you to attack means the mechanic has an unusually high built-in risk. Many recent formats have been dominated by huge creatures like Lovestruck Beast or Uro, which make it difficult to imagine using such attack triggers more than once. So, other than Robber of the Rich — which can consistently attack and trigger on turn two — not that many small ground attackers have been seen in Standard. Cynical minds will be evaluating these boast creatures as though you are essentially sacrificing them to use the ability — and in some cases, that will be good enough!


Magic is already subject to a ton of randomness for a competitive game, and players tend to be risk-averse. One of the easiest ways for a mechanic to “miss” is for it to be too reliant on variance. This can be randomness built into the mechanic itself, but also things like creature auras which come with a built-in vulnerability to removal. WotC seem to be aware of this potential resistance to boast, and have compensated by making the effects so far very powerful for their cost. With an enticing enough payoff, players can start to build their decks around improving their average return on boast. With just a bit of extra removal or the right combat tricks, you can ensure your creature can survive any blockers and boast again next turn, thus cementing your advantage. 

This is another reason why tying these abilities to combat is so interesting from a design perspective. The wording of boast allows R&D to balance the design of utility creatures by altering how reliably they attack or trade, without the issue of losing to chump blocks like the more common “combat damage to a player” triggers. Another cool facet of building boast around combat is the impressive variation between timing opportunities available. Most of these abilities will be legal to activate as soon as attacks are declared: before blockers, as well as after blockers, after damage, or even during your second main phase. And when each boast effect has a different optimal window, it makes the specific puzzles and patterns different for each one, despite them all using the same base mechanic!

Varragoth, Bloodsky Sire

The sheer variety in play patterns is obvious even with only a handful of boast cards spoiled. Varragoth, Bloodsky Sire is a three-mana 2/3, and thus can’t be assumed to have safe attacks very often. But it does have deathtouch to enforce trades, and its boast ability is both cheap and very powerful — even backbreaking if activated across consecutive turns. The opponent is pressured to block and kill it to stop the value, but will be forced to trade down — and you still get the first boast activation regardless.

Eradicator Valkyrie

Eradicator Valkyrie is an extremely reliable attacker whose boast is cheap but situational. It’s also a boast ability which offers extra merit when activated immediately before blockers, allowing the Valkyrie to brush aside potential flying walls like Dream Trawler unless they’re accompanied by extra sacrifice fodder.

This is the kind of flexible and fundamentally choice-driven design that has made deciduous mechanics like kicker and flashback so good. I wouldn’t be sad to see boast become a more consistent part of the game as well! But no point talking too big about it yet — we’ll see what tall tales we can tell in Kaldheim first.