Gateways to Eternity is a Minecraft mod that allows creating data-driven gameplay events called Gateways.

Gateways are a wave-based combat event. For each wave, a set group of enemies will spawn; progressing to the next wave requires killing all enemies before the timer elapses.
Completion of waves grants rewards to the player(s), and completion of the entire Gateway can provide additional benefits.

See the CurseForge Page for the full description.

For information on adding custom gateways, see the schema. A basic understanding of how to add datapack content is required.