While outside the world border, I take tons of damage and would like to find a way to heal more than my previous solution.
I am using world border as a function in my minigame and being out of world border is part of the minigame as world border size will shrink to 0 forcing players to heal up.
My way to survive being outside the border currently is to use Lingering Potions of Healing 2. This way was still not fast enough and I died.
Here is the world border settings:
/worldborder damage buffer 0 /worldborder damage amount 17.5 /worldborder center ~10 ~10 /worldborder set 10