Thrull is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

How it works : Thrull

Original English text — Wizards of the Coast / Scryfall

No additional ruling has been published for this card.

Interactions with other cards

These cards' text mentions Thrull.

Endrek Sahr, Master Breeder

Whenever you cast a creature spell, create X 1/1 black Thrull creature tokens, where X is that spell's mana value. When you control seven or more Thrulls, sacrifice Endrek Sahr.

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens. +1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander. −10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control. Tevesh Szat, Doom of Fools can be your commander. Partner

Szat's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead. • Each opponent sacrifices a creature they control with the greatest power. • Exile all opponents' graveyards, then create X 0/1 black Thrull creature tokens, where X is the greatest power among creature cards exiled this way.

Soul Exchange

As an additional cost to cast this spell, exile a creature you control. Return target creature card from your graveyard to the battlefield. Put a +2/+2 counter on that creature if the exiled creature was a Thrull.

Orzhov Keyrune

{T}: Add {W} or {B}. {W}{B}: This artifact becomes a 1/4 white and black Thrull artifact creature with lifelink until end of turn.

Sarpadian Empires, Vol. VII

As this artifact enters, choose white Citizen, blue Camarid, black Thrull, red Goblin, or green Saproling. {3}, {T}: Create a 1/1 creature token of the chosen color and type.

Breeding Pit

At the beginning of your upkeep, sacrifice this enchantment unless you pay {B}{B}. At the beginning of your end step, create a 0/1 black Thrull creature token.

Ebon Praetor

First strike, trample At the beginning of your upkeep, put a -2/-2 counter on this creature. Sacrifice a creature: Remove a -2/-2 counter from this creature. If the sacrificed creature was a Thrull, put a +1/+0 counter on this creature. Activate only during your upkeep and only once each turn.

Thrull Champion

Thrull creatures get +1/+1. {T}: Gain control of target Thrull for as long as you control this creature.

Tourach's Gate

Enchant land you control Sacrifice a Thrull: Put three time counters on this Aura. At the beginning of your upkeep, remove a time counter from this Aura. If there are no time counters on this Aura, sacrifice it. Tap enchanted land: Attacking creatures you control get +2/-1 until end of turn. Activate only if enchanted land is untapped.