Use Magic Device (CHA):
The outer planes look with beneficial eyes those who believe, and sometimes respond to their wills. As a full round action that give attacks of opportunity, with a successful check (DC 30) the character can try activate a portal blindly, provided the character has enough things to shove off into the arch. Once the portal activates, the character must jump immediately (his next action) or he’ll need to open it again.
Use Psionic Device (CHA):
Retry: Only if the unmodified roll was higher than 4.
Special: On a natural roll of 1-4 the character is unable to open the portal (it doesn't matter the DC he succeeded in, the key is too complicated, or time-related). You can take 20 in this check only if there’s no danger around, and you still have to roll, if a 1-4 is rolled the attempt fails and 20 rounds are wasted in vain.