Yethantag

Yethantag is a Old-Nintenian word for Apocalypse. It can start if a group of 100 individuals gather in a cave, preform several rituals, and sacrifice 7 well-known citizens. Afterwards you strap the person who started the gathering and/or lead it onto a wooden pole. If you've done all the previous rituals the pole should catch on fire, including the person on the pole, and that person would then transform in to a portal allowing the Gise to enter the Overworld.

The closest time a summoning could have happened what when a group of people, now know as the Arkizien, tried to summon him and almost did. All they needed to do was put the leader on the pole. Before they could do that, a Nintenian official heard news of the event and imprisoned all of the participants. Since the current king thought they were to dangerous to even be on the planet, even if they were dead, he banished them to Arkizer.