(As I am a huge fans of +1/+1 counters, most large sets that I lead design tend to fall in this category.) A recent non-+1/+1 counter block was Champions of Kamigawa
Invasion of New Capenna // Holy Frazzle-Cannon is a nice flexible removal and has the potential to become a great tribal support card as the Holy Frazzle-Cannon has Whenever equipped creature attacks, put a +1/+1 counter on that creature and each other creature you control that shares a creature type with it. Murderous Rider // Swift End is a great card since it is a Zombie, it combines target removal at instant speed for and self-recursion at library, so it has the potential to be used more than once
Combo decks in these formats have traditionally avoided tutors in favor of cantripping or looting through their cards quickly, but that may be worth rethinking for black-based lists like Yawgmoth Toolbox
If a creature's power is 2 or less when it enters but becomes greater than 2 while Irreverent Gremlin's second ability is still on the stack, you'll still have the choice to discard a card when the ability resolves
When designers who didn't know the reference asked about him, I just said, "Trust me, he's great." Later when working on reprints, I also wanted to reference the Wondrous Tails weekly missions, and Tome of Legends felt like the perfect flavor fit by adding counters to your book and granting you rewards for doing so
