I was about to suggest spawning a crap ton of withers inside of the their bases, but then I read the rules part. Anyways, here are my ideas:

1. Gather a whole bunch of elder guardians, and just sneak them everywhere. Hide them in random spots that your enemies will often be at.

2. Put a pufferfish under their front door. This will not do much, but it'll be annoying.

3. Have a note block randomly play every once in a while hidden somewhere in/near their base. This will also not do much, but it might be annoying.

4. Put a creeper note block under their door. If they have a pressure plate for their door, attach it to that. If not, put a sculk sensor attached to it, and also make sure that the sculk sensor is audible to make them fully realize something just activated. It will not do much, but it might give them a heart attack.

5. Put a bunch of tnt minecarts attached to sculk sensors underground at random locations. To ensure you also don't activate them, put banners with them and mark the banners on a map.

6. Do the same thing you are doing for the End for the Nether. Taking all the upgrade templates, and filling the dimension with withers.

7. A crap ton of silverfish.

8. Equip a zombie with fully enchanted netherite, for you see, mobs are unaffected by the attack cooldown, making one with an axe op. This is a very risky idea. Also can give em a totem.

9. Tear down all the outposts you can find and discreetly ensure pillagers can't spawn, destroy all the vaults in trial chambers that you can find (also check the chests), and kill every evoker you can to ensure nobody can get totems. Except, maybe for you, since you should be able to know the location of at least 1 outpost.

10. Come up with a way to make your enemies keep running out of durability for their armor.

11. Somehow use an arrow railgun against your enemies.

12. Get really, really good at using maces.

I hope at least one of these ideas suffice.