My group had an interesting campaign where slaadi would regularly show up and randomly help the players or ask the players to do something, which was invariably a lot easier than expected and heavily rewarded.
When it came to helping, they would sometimes join in defeating a tough foe, handing over a potion that turns out to be needed, or helping the party bypass some obstacle.
When it came to things asked, sometimes it was as simple as stopping a particular thief, buying a bunch of bananas, giving a sack full of gold to a random beggar... basically, things that made no sense and which anyone could do.
Eventually, a bunch of modrons showed up, informed the PCs they had set up the entire plot the PCs were foiling specifically to create heroes who could help fight against the Slaad, and were ending it because the Slaad were helping them not only accomplish it, but do a better job than expected. And the Modrons couldn't figure out why. See, it turned out that everything the slaad had asked the PCs to do was in some way foiling one of the BBEG's plots.
The PCs, when they confronted their slaad contact about it, merely got three times the pay they were promised for the latest mission they were sent on, congratulated for doing a good job, and left. The PCs spent the rest of the campaign trying to figure out if the slaad had honestly wanted them to succeed, or if the slaad were trying to make it appear so in order to mind screw the modrons.