If a villain uses a permanent teleportation circle for the linked portal ritual, say, to flee from threatening PCs, must the villain use an arcana roll to determine how long the portal remains open after him? Can he close the portal immediately after his use to prevent them from following him?
I can't seem to find any specific rules about teleportation circles (via the Compendium, at least), aside from the rituals themselves. The wording of the Linked Portal ritual is: "At the completion of this ritual, make an Arcana check. The result determines the duration that the portal remains open."
Yes, I realize that said rule is for PC use and that NPCs, etc. abide by different rules, but I would like there to be consistency in the game world (why would a teleportation circle work differently for the PCs than NPCs?), and arbitrarily ruling the villian can escape this way when it's beyond the rules feels like a (mis)application of DM Force.