Shadowverse

As for the portal, I have a feeling that the meta is different, and what seems like useless junk in the rotation suddenly becomes a must-have in unlimited.

Well, I don't know, I can still understand the cat creatures (like, wards are more important in unlimited), but two Sapphires is just plain weird. Even in the rotation, there are cases where you can't win with your board, and discarding three Sapphires allows you to concede. In unlimited (the realm of Themis, Bahamut, and other purgatories), it's even more so. It seems like instead of the third Sapphire, there are Ironforge-enhanced creatures, but it's more stable. And about substitution and the Rift, Locken has already written everything about it.