By holding this rune-carved rod on both sides of the portal, you stabilize the link between the two places.
Wondrous Item 5,000 gp
Power Daily (Minor Action)
Until the end of your next turn, one adjacent portal opened with the Linked Portal, Planar Portal, Reverse Portal, or True Portal ritual remains open, even if it would normally close before then.
Sustain Minor: The effect persists until the end of your next turn. After 10 rounds of sustaining this effect, you can no longer sustain it and the portal closes. The portal begins to waver after 5 rounds, warning you of its impending closure.
Published in Dragon Magazine 387, page(s) 29.