Krenko, Mob Boss If goblins or red aggression are your thing, Krenko, Mob Boss is a fine choice
Amethyst/Ruby can be useful for control decks focused on maintaining sway over the board, while a good Emerald/Steel build tends to angle for weakening an opponent by depleting their resources through discard abilities
That's knocked it down in price a fair bit, though the Ultra-Premium Collections are so costly, even their promo is worth quite a lot
Take note, these are unconfirmed leaks from a third party source so view at your own discretion
New, format-specific support cards like Dose of Dawnglow are proving to be more efficient than older engines
Lastly, Subversive Acolyte is having its mana cost shifted from BB to 1B so it can go it in more decks, while having its toughness bumped up a point in combination with the second ability giving the creature +3+2 instead of +3+3 to make its new form still resemble Phyrexian Negator