Affinity for creatures (This spell costs less to cast for each creature you control.)
Flying, deathtouch
Instant and sorcery spells you cast have affinity for creatures.
Flood the board with creatures, then deploy Witherbloom for cheap (affinity makes the 8-drop castable for as little as a couple mana) as a flying deathtouch threat. With it out, your removal, card draw, and big X-spells become dirt-cheap, letting you out-resource and out-grind every opponent before closing with a wide board or a single overloaded spell.
Massive cost reduction on both the commander and your entire instant/sorcery suite once you go wide
BG gives best-in-class removal, recursion, and ramp to refuel the board
Flying + deathtouch makes Witherbloom a strong attacker and defensive wall
Synergizes with token producers to enable game-warping cheap X-spells
Affinity does nothing if your board is empty, so board wipes set you back hard
An 8-mana commander is punishing to recast if it dies repeatedly without creatures
No evasion or protection for the wider team beyond the dragon itself
Relies on resolving creatures first, making it vulnerable to early disruption and stax
Recurs your best removal or X-spell, which then costs almost nothing to recast.
Add more reliable token engines (Bitterblossom, Ophiomancer, Mycoloth) and token doublers to keep affinity online through wipes. Tighten the mana with fast rocks and dorks so you can deploy creatures early, then leverage cheap tutors (Demonic Tutor, Diabolic Intent) to find your finishing X-spell. Top-end consistency comes from recursion like Eternal Witness and Meren plus a backup wincon such as Craterhoof Behemoth for resilience against grindy tables.