They confer about optimal strategies and lines which Pokmon to play next, which support cards are going to be useful, the optimal path to a win
You should definitely check out the mechanics article to get a full sense of what's going onor, for a shorter bite-size version, check out these videos that cover the mechanics in depth: Welcome to Kaladesh It's a brand-new block, and it's hard to find a better time to come check out a Prerelease
Suicune EX Card Overview HP : 140 ATK : 20x Text : [Crystal Waltz] This attack does 20 damage for each Benched Pokemon (both yours and your opponents)
In Historic Brawl A lot of the specialize cards would make interesting commanders in Historic Brawl
Control decks absolutely needed this card to have a chance at thriving in this format, and I could see it being played in midrange decks as well
Nekroz of Trishula is the ritual version of Trishula, Dragon of the Ice Barrier (you know, that monster so good its still limited to 1 copy per deck to this day?) When this card is ritual summoned you can banish 3 of your opponents cards, one each from their hand, field, and graveyard