mtg ravnica allegiance cards Booster Pack Draft : (RNA) — Twenty Sided A conflict that could tear apart the world itself looms large Ravnica Allegiance - MTG Wiki

This is far from the first time weve seen an MTG promo showcased without rules text

When that spell or ability resolves, the uncounterable spell won't be countered, but any additional effects of the countering spell or ability will still happen

The real winning play here is to play it in decks that make tokens off the spells that you cast, think things like Raise the Alarm or Increasing Devotion

Buffing a creatures power or giving it an ability like deathtouch is an excellent way to handle defender creatures

Its not unreasonable to think you might just draw twenty cards, right there, and if your deck contains a very unusual amount of mana, you might not be far from drawing your whole deck (especially if youve got a couple of Dakmor Salvages somewhere in the mix, making it completely deterministic that you mill your deck, fill the battlefield, and set up some graveyard kill)

If youre running it while focusing on enchantments, you want a critical mass of them