Your have a small extradimensional space which appears on your person (Players choose how it is shown on them). The space can be used to keep your companions or pets in on quests where pets aren't allowed or are only allowed for roleplay only. The extradimensional space cannot be used for any other purpose except for bringing pets/companions on quests.
Companions or pets who are willing to enter the extradimensional space with permission from you can have their size changed to tiny upon interacting with the space. Companions or pets in this space can only affect and be affected by other creatures in the extradimensional space.
Companions and pets in this extradimensional space can peek out of the space from time to time and might aid them on the quest in little ways. (DM's discretion)
Comments