Gizmos and Death Traps

We learn the real reason of Jayce's strange behavior of the events in season 2 because he was infected an evil essence called Dread Magic that will consume the world!

It was created by a foolish wizard who tried to increase his abilities, however it's not normal magic its malicious, hatred and hungry it doesn't need any spells or totems. It spreads without limits and takes over its host, corrupt anyone or anything into a destructive being only the urge to destroy the world.

Thats explains back in the Bermuda Triangle why some of the alchemists are strange looking with different abilities and why they lock Jayce in the soul box and become demon with a peculiar behavior. And in the sacred forge because the Pie Maker have that same reaction when Jayce spread her with Dread Magic.

And that how dread magic was created to be sealed away from the world.