[Sombre]

You use #firstshape which will trigger at the end of any battle or the end of any turn. This can be used with multiple unit IDs to make something which changes slowly over time, like llamabeast's corpse eating wendigo, or an egg that takes 12 months to hatch (would require,.. 13 or 14 unit ids).

And yes they can point to the same thing. All the summons can.