Spirit yaks are farm animals which can be obtained by making pack yak pouches or by breeding two yaks in the breeding pen. Currently players must have a free inventory space to receive a spirit yak whilst creating pouches.
It requires level 71 Farming to check.
Upon obtaining a spirit yak, it'll be placed in the inventory and the player receives the following message: Essence from beyond this plane forms into a baby yak in your backpack.
- ^ 1/5000 chance.
- ^ Jagex. Mod Rowley's Twitter account. 7 September 2018. (Archived from the original on 7 September 2018.) Mod Rowley: "If going for a spirit yak from crafting pack yak pouches, make sure to keep an inventory space clear. Hopefully, we can get this changed so it replaces a pack yak pouch (like golden rocks do) at some point (but it won't be ahead of this weekend)."