Mechanics

GMOD does not have any form of built-in healing system. Starting at 1.0.4.0, Horde implemented its own healing system which YOU MUST USE if you want any buffs/statistics from Horde to apply.

Use HORDE:OnPlayerHeal(self, healinfo) to apply healing. Use Horde_OnPlayerHeal(ply, healinfo) hook for healing detection. See https://github.com/tpan496/Horde/blob/main/gamemode/sv_heal.lua.

Example

local healinfo = HealInfo:New({amount=5, healer=ply_healer})
HORDE:OnPlayerHeal(ply_to_be_healed, healinfo)

Note

You DO NOT NEED TO CHECK MAX HEALTH of players to apply healing; this is already handled by Horde.