Chronarch

Guards the last gate so faithfully that even time knocks before entering.

Forms

The same creature at each step of its evolution. A form is crafted from the one before it, so the ladder is climbed in order.

This creature has a shiny version at every step of the ladder. Shiny is its own roll, so it can turn up on a plain form or on a fully evolved one.

Chronarch hatches from the End of Time egg. Every egg you open in that world can give you one, and the rarer the creature the longer that takes.