The Nightosphere Portal is a portal used to access and/or leave the Nightosphere. Finn and Jake use it when entering and leaving the Nightosphere. Marceline also uses it to chase Finn and Jake back to the real world. She can open and close the portal from the Nightosphere and leave it open as long as she wants, being associated with the Lord of Evil.
To create a portal, Marceline says you have to draw a happy face, douse it with bug milk and chant a fel incantation in Latin (Maloso vobiscum et cum spiritum!).
- The happy face used by Finn to open the portal is a PHIL FACE.
- The incantation to open the Nightosphere is Dog Latin, and presumably is supposed to mean "evil be with you and with your spirit." An approximation in correct Latin would be "malum sit uobiscum et cum spiritu."
- The portal spell is an allusion to the salutation/blessing Dominus vobiscum/Pax vobis. Et cum spiritu tuo. used in Catholic Mass and some other Christian denominations.
- The portal takes on two distinct appearences, sometimes taking the for of an entryway leading into fire, and others as a blue swirl.