When looking through the set listing for Planeshift, an alternate card shows up along with the actual card for the set for several legendary cards. In digging into them they appear to show as being part of the set, but in fact are not. Not really sure what's going on with that set.
I’ll check if scryfall can fix it
Ah, so Scryfall is wrong, that might be trickier to get corrected.
To be fair, those are alt art foils that predate that really being a thing for the three cards it was done with.
Well it is in according to scryfall: https://scryfall.com/card/pls/74%E2%98%85/tahngarth-talruum-hero