B-I-N-G-O

Trample
Whenever a player casts a spell, put a chip counter on its mana value.
This creature gets +9/+9 for each set of three numbers in a row with chip counters on them.

The List (Unfinity Foil Edition)

Unsanctioned

Trample
Whenever a player casts a spell, put a chip counter on its converted mana cost.
B-I-N-G-O gets +9/+9 for each set of three numbers in a row with chip counters on them.

Unhinged

Trample
Whenever a player plays a spell, put a chip counter on its converted mana cost.
B-I-N-G-O gets +9/+9 for each set of three numbers in a row with chip counters on them.

All nine rows count. You can fill rows horizontally, vertically, and diagonally. A full card with give B-I-N-G-O +72/+72.

Casting multiple spells with the same mana value has no additional benefit. Once a spot has a chip counter, it's marked, and additional chip counters won't do anything.

The counters are considered to be on the inherent tracker in B-I-N-G-O's art, not on the creature itself. Those counters can't be removed or moved to another permanent. Similarly, if you proliferate, you can't add more chip counters to B-I-N-G-O.