-- A player leveled up
function GameMode:OnPlayerLevelUp(keys)
    DebugPrint('[BAREBONES] OnPlayerLevelUp')
    DebugPrintTable(keys)

    local player = EntIndexToHScript(keys.player)
    local level = keys.level

    local hero = player:GetAssignedHero()
    -- Another way (recommended). Ensure you create a GameMode.heroes table and populate it accordingly:
    local hero = self.heroes[player:GetPlayerID()]
end