I love it in ramp to win the game and make your other big stuff trample, madness, discard matters, Golgari self-mill, Jund's Lord Windgrace lands return to the battlefield from the graveyard, Sultai's self-milling Sidisi, Brood Tyrant, blink, midrange, tokens, and loads more
The mana value of the spell is determined by only its mana cost, no matter what the total cost to cast that spell was
Starting with these partner pairs is the tip of an immense iceberg
But I also want to look out for cards that were excluded from the precon, like Ebonblade Reaper, which can drastically change an opponents place in the game, or Primordial Mist, which can turn manifested instants or sorceries back into spells