But can you build a bilge deck splashing 3 teemos and no other non bilge cards?
You could not. Your deck's only region at this point is "Bilgewater" and neither of Teemo's regions are BW.
You'd need at least 1 single-region Bandle City card or P&Z card.
Multi-Region cards are basically ignored when determining your deck's regions. But they can be added to your deck if it is either one of their regions.
So wouldn't that means that the possible 3 teemo's + 37 BW card deck would retroactively become illegal after this expansion?
Yes, you are correct. It will have to change by at least 1 card to be legal.
Some specific deck possibilities for Teemo, Lulu, Fizz, and Heimerdinger that were possible will no longer be, but a much higher number of new possibilities will be opening to them.
You may find a Bandle City card that makes that old BW + Teemo deck even stronger.
Riot_DanCast
You could not. Your deck's only region at this point is "Bilgewater" and neither of Teemo's regions are BW.
You'd need at least 1 single-region Bandle City card or P&Z card.
Multi-Region cards are basically ignored when determining your deck's regions. But they can be added to your deck if it is either one of their regions.
Riot_DanCast
Yes, you are correct. It will have to change by at least 1 card to be legal.
Some specific deck possibilities for Teemo, Lulu, Fizz, and Heimerdinger that were possible will no longer be, but a much higher number of new possibilities will be opening to them.
You may find a Bandle City card that makes that old BW + Teemo deck even stronger.