Birgi, God of Storytelling // Harnfel, Horn of Bounty

Cast-triggered mana that survives steps and phases is a subtle reward for spell-density decks: each spell you cast refunds a red, and because that mana persists rather than emptying at end of phase, it chains forward into the next cast instead of fizzling. The timing is the wrinkle. A ritual nets you mana ahead of a spell; this pays you back after the fact, so the value only accrues where a string of cheap red spells each funds the one behind it. The boast clause is a quieter note, and worth reading precisely: boast only fires on creatures that attacked, and doubling it lets an attacker pay its boast cost twice per turn rather than once. It reads more as a mechanical tie-in than a reason to run the card. Harnfel is the other lane entirely, converting excess cards into raw advantage by exiling the top two of your library per discard and letting you play them that turn: impulse draw priced as a discard outlet. That is the through-line worth naming. Committing to one face on entry forces a choice, and the two halves want opposite fuel: the front wants spells in hand to cast, the back wants a full library and cards to pitch. Each side punishes a hand that sits still and rewards a deck that spends everything it draws.