Bunbun is a very good card, despite its appearence. It has quite solid bulk with 5 HP for 4 cost, but is vulnerable to Muffet's Pet due to its mere 2 ATK. That's where Bun comes in, of which one is summoned when Bunbun is played.
The Bun is not something to brag about in terms of stats. It's a free 1/1 monster, same as Tiny Froggit. However, when it dies, all Bunbun on your board will gain +3 ATK.
As mentioend before, when Bun dies, all ally Bunbun gain +3 ATK. This makes placing 2 Bunbuns together very powerful, filling your board with 2 of them and 2 Buns. And when the Buns die, both Bunbun gain +6 ATK for a total of 8 ATK each.
This makes Bunbun very good in multiple decks for different reasons.
- Integrity: You can get more Bun's by using Break or Royal Integrity on your Bunbun.
- Bravery: With one Bunbun, you can use Assault to give a Bun Haste and let it attack a monster and kill itself right away. Afterwards, you can potentially use Overheat to deal massive DMG to all monsters. Overgrowth is able to buff the Buns, but this isn't really impactful in most situations.
Some counters can be very easy to do, especially if the user didn't kill their own Bun right away.
- Killing Bunbun before killing Bun (which, as mentioned, can be done with Muffet's Pet).
- Silence the Bun, best done with Scarf Mouse or Penetration to save Gold.
But there are other options if they have done so.
- Silence Bunbun, returning its ATK back to 2. This time, Nacarat Jester can also be worth using.
- Using Ugly Fish to reduce Bunbun's ATK directly, but this requires a turn (or another card like Assault or Pie.
- Buns on the Beach (by Asrite)
- Originally available through Summer Pack Bundle.