Bug: Hellkite tyrant (copy?) returns artifacts to their owner when exiled

Reported from discord:
> hellkite tyrant delina copy did combat damage, then when it exiled everything went back to their owner instead of me keeping the stolen artifacts

[[Hellkite Tyrant]] [[Delina, Wild Mage]]
I didn't attempt to replicate the bug.

First reproduce the reported interaction between Hellkite Tyrant and a Delina, Wild Mage copy, since the report was not replicated. Then inspect the implementations and related tests for these cards and verify the expected artifact ownership after the copied creature is exiled.

Written by the indexing model from the issue text.