execute if score @s MaxHealth matches 13 run attribute @s minecraft:generic.max_health base set 13
execute if score @s MaxHealth matches 14 run attribute @s minecraft:generic.max_health base set 14
execute if score @s MaxHealth matches 15 run attribute @s minecraft:generic.max_health base set 15
execute if score @s MaxHealth matches 16 run attribute @s minecraft:generic.max_health base set 16