As with all Secret Lair drops, the cards will be themed variants on existing MTG cards, rather than brand new cards: Puresteel Paladin (Ash)
They can still tap for mana, so you aren't forcing them to have a bunch of Mountains out, but this is a nice and friendlier way to attack people who abuse lands precisely because they are harder to answer and people feel uncomfortable playing land-answers
Here are a few of its more expensive cards, and their current price on the secondary market
Book 2 is set up after Zhao, the Moon Slayer is quickly taken down
10 PACKS + 1 COLLECTOR BOOSTER
Theres a good chance you wouldnt want to use her in challenges anyway, because she comes packing a massive three lore to help speed you towards victory