He was an ice god who brought the ice age to the Earth and wanted to bring another. But he could not as he was imprisoned and could not escape the mound he was trapped in.
He was awakened by Morgan, but Morgan did it wrong, so Golgoth was awake but still trapped. Golgoth killed Morgan and tried to get Tom to kick the candle circle down. Tom said no so Golgoth started to kill him. But sunrise came and his powers weakened.
Golgoth was once again trapped. The spook later rescued tom frm the mound, and destroyed the Grimoire, meaning no-one could ever summon Golgoth again.