Like most Pokmon cards, the value of Ledian depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (HeartGold & SoulSilver)
You can Airbend expensive artifacts or creatures to save them from a board wipe, then cast them for cheap on your next turn to trigger all your Cast from Exile payoffs
With Phyrexian Altar, you can do something similar
3 Pokmon TCG: Shining Fates booster packs, each containing 10 cards and 1 basic Energy
Without all the expenses of getting cards slabbed/graded, I can sell High Value Singles & Premium Re+Packs for a lot less so you get more for your money
The fact that it is better to keep red-eyed mobs in the graveyard rather than returning them to the deck has become more meaningful thanks to the return of Black Dragoon, which can be drawn by deck fusion with the Red Eyes fusion that will follow Black Jackie Chan