These are reprints from the first Lord of the Rings MTG set, with variably hard-to-read text, and they'll be in the main set, not a Secret Lair
There are even a couple five-color lands that make colorless in the format: Haven of the Spirit Dragon, Crucible of the Spirit Dragon, and Ally Encampment
For card advantage, things like Fact or Fiction and similar cards let you present interesting choices to other players to stay on the Dungeon Master theme while still gaining advantage
That alone is worth a free +1/+1 to your team for the turn, though the triggered ability gets way more interesting when you have multiple sources gaining energy each turn
Purging Stormbrood Purging Stormbrood comes in swinging as a 4/4 flier, but it also strips counters off a creature when it enters
It may not police the board like Rhystic Study, but it can create a tidal wave of card advantage when paired with the right engines