You score points for "conquering" a battlefield, or for holding on to one until the start of your turn. With two battlefields in a 1v1 game (the one you bring and the one your opponent brings), you can normally only get two points per turn. When someone gets their 8th point, they win.

The biggest difference between MTG and Riftbound is the emphasis on movement and "action economy". Rather than a combat phase, there's a fight every time creatures ("units") move to an occupied battlefield card. You tap units to move them so this limits your actions, but is where strategy comes in.

Rather than attack your opponent directly, you are both attacking battlefield cards to score points. They have symmetrical effects like "everyone here has +2 Might". Each player brings three, and you pick one per game based on e.g. what your deck wants to do, whether you want control or aggro, etc.

Every turn you play 2 lands ("runes") from a special 12 card deck. Colours are determined by your Legend, but you can have whatever ratio you like. Can tap them for Energy (generic mana) and/or return them to the bottom of the rune deck for Power (coloured pips). So powerful plays set you back.

40 card, 3-copy-limit. Commander split into "legend" (sets deck colour id, not a creature but has an always-on ability) and "champion" (creature you can play from command zone, but doesn't return on death). There are 6 colours, and each pair (except "enemy colours") has a legend (with more coming).