In case you missed the updated tip in the latest beta build, Battle for Azeroth will allow you to have 18 characters per realm. The 50 characters per account cap remains in place.
Read next
[ES/EN] Splinterlands – Battle Challenge – Guide #2: Battle 3 | Battle 4durlan · 
18 Mana Battle Perfect Strategy Wins the Day — Easy 18 Mana Battlealiakbar2 · 
I Am Still One of The OG in Small Mana Cap Battledewabrata · 
Splinterlands: A battle in which I inflicted significant strategic damage on the opponent even before the battle began!🔥untilwelearn ·
From @bboyabluka