With summons, you can keep them around permanently by constantly making token copies of them before the last lore counter is put on them
If you have a box of commons and uncommons lying around, throw it up on eBay for $10-20 and see if anything sticks
But just like Pokmon and Magic: The Gathering, some Lorcana cards are worth significantly more than others, especially those tied to early releases, exclusive foils, or competitive play value
Thanks to her No Place Id Rather Be ability, you can play her if shes in your discard
Or, if you can content yourself with four exiled cards each go, you can bounce it to your hand with cards like Crystal Shard
This insert has a timeline of Teferi's life, from his childhood at the Academy to the War of the Spark