Chimil gave the Oltec time. Ojer Pakpatiq gave them the tools to learn its lessons.

Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time

(Transforms from Ojer Pakpatiq, Deepest Epoch.)
{T}: Add {U}. Remove a time counter from Temple of Cyclical Time.
{2}{U}, {T}: Transform Temple of Cyclical Time. Activate only if it has no time counters on it and only as a sorcery.

Flying
Whenever you cast an instant spell from your hand, it gains rebound. (Exile it as it resolves. At the beginning of your next upkeep, you may cast it from exile without paying its mana cost.)
When Ojer Pakpatiq dies, return it to the battlefield tapped and transformed under its owner's control with three time counters on it.

The Lost Caverns of Ixalan

The Lost Caverns of Ixalan Promos

Casting the card again due to rebound's delayed triggered ability is optional. If you choose not to cast the card, or if you can't because an effect prohibits it, the card will stay exiled. You won't get another chance to cast it on a future turn. If you do cast the card, it's put into its owner's graveyard as normal once it resolves.

If a card that isn't a transforming double-faced card is a copy of Ojer Pakpatiq, Deepest Epoch, it won't return to the battlefield when it dies.

If a spell with rebound that you cast from your hand doesn't resolve for any reason, including being countered, that spell won't resolve and none of its effects will happen, including rebound. The spell will be put into its owner's graveyard and you won't get to cast it again on your next turn.