If it comes down to sacrificing two tapped Mountains to get more goblins, just be sure you can finish the game quickly
Providing the means to make creatures unblockable is underrated in Commander, especially in Bracket 2 (Core) games where precons usually find themselves
We're updating the Welcome Booster with every main set release, so they'll have a Zendikar spin compared to M21
Combos Early combos are mainly about using Rush or Exert ability characters, and trying to keep your characters just hanging on
Merciless Executioner is good for token decks that always have an irrelevant 1/1 lying around to sacrifice while your opponents lose real threats, or in decks that can repeatedly get this trigger like Meren of Clan Nel Toth
Phantom Train is the gold standard, often running away with games in a few attacks due to the lack of good removal