Onion San was added in Beta 5.9 after multiple requests. Previous Versions can be found here.
Left Tentacle-0
Onion San has the Magic ability of summoning two Tentacles to the board adjacent to it upon placement. These are:
  • Left Tentacle, 1 ATK, 3 HP, 2G
    • Dust: Deal 3 damage to your opponent.
  • Right Tentacle, 3 ATK, 1 HP, 2G
    • Dust: Restore 3 HP to its owner.

If an adjacent slot isn't available next to Onion San then the respective Tentacle won't appear (e.g. if the card slot left of Onion San is taken or doesn't exist then the Left Tentacle won't be summoned).

Right Tentacle-0
Because of Onion San's ability to summon an additional 2 cards for free, as well as its good stat/cost ratio, it's useful in most decks, however in particular Integrity, with favourable use in Kindness or Justice.

Works very well with cards like Politics Bear and Nice Cream Guy.