Let me guide you through "ideal" board state for you to start taking infinite turns:
You need at least 3 lands, one of them has to produce white mana. Then you need both powerstone shards, gift of paradise, Teferi, magistrate's scepter, Skyship Plunderer and Sleep. Additionally playing Oath of Teferi would also be pretty good (but can be done after you achieve the loop).
Your first few turns you're busy getting shards & gift of paradise into play. But on turn 2 (when you can't play them yet) you play plunderer. After you play both shards and gift and the other plunderer, you have to play Teferi. Only after that you should to play magistrate's scepter. Also you need to cast sleep on the same turn (remember that you only have 3 lands). So then you tap one of untapped shards and tap scepter for the first time. Here I get to yet another conundrum: I was planning to run 4 shards, but I realised that without gift, and especially its life gain your chances of survival long enough to get going get lower. But here's the problem with 4 shards, you needed to tap just one to get once counter on the scepter, now you need to tap both. So this probably adds yet another turn. But attacking with two plunderers during after sleep solves this. So now you have 3 counters on it, but it's currently tapped. So you use Teferi's +2 ability to untap it, and take another turn. Given that opponent's creatures don't untap, you repeat the process and take the next turn. So you're basically taking infinite turns at this rate.
