Keep the 10 maps (no new additions). Better rules can allow the "variety" while keeping the "balance of choices".
Example using Player A (highest ELO) and Player B (lowest ELO).
Player B picks the Map.
Player A picks any Loc.
Player B picks any Loc, but NOT adjacent to Player B.
With this proceeding, the fixed choices aren't needed, which adds variety and makes picking simpler.
Player B picks Shadow Realm.
Player A picks Loc 6 (top-right corner).
Player B can pick any from Locs 2-3-4 (NOT 1-5 because are adjacent to Loc 6).