Kaalia of the Vast can cheat it from your hand (since it's a dragon), Yuna, Hope of Spira can bring it back from your graveyard (since it's an enchantment), and Esper Terra can copy it and trigger most of Bahamut's value by advancing three chapters: Summon: Bahamut isnt legendary, so Esper Terra has no problem copying it
Venser also makes random other cards way stronger, like Nasty End sacrifice The Hollow to draw 3 cards for 2 mana, Vat of Rebirth gets loaded with oil as The Hollow dies, or Ringsight to give Venser skulk so we can bypass blockers while tutoring up a card
Every turn, you get to add a +1/+1 counter to any creature, slowly helping to pump your team or to start punching through with a solitary attacker
This two-card infinite combo wins the game, and you always have access to half of it
Doubling a creatures power is no joke, and the ability to do it multiple times off multiple landfall triggers is heinous
Ill be honest: I was surprised at first