((All right, here goes. This is the full plan for stopping the volcano.
Viznor-speak will not be included in this post, because as nice as it is to not be a tad meta, it'd just end up giving everyone a headache.))
Time to coordinate the massive disaster-averting spell. Hoping to make a permanent solution here.
The affinities we have:
Aether (2X)
Summoning (2X)
Healing
Physicality
Blades
Luck
Glass (from item)
Use my yes/no book to check for subterfuge, as per usual. If anyone is hijacking or otherwise messing with it, disallow them from contributing and direct more power to parts of the spell that don't use their affinity to compensate.
With that in mind...
Let's weave a sort of magical shell around the portal-tree, essentially a construct designed to contain everything inside (and prevent outside interference). It should have...
Containment stuff:
-A physicality/binding system which keeps all material which exits the portal from leaving its immediate vicinity. This includes fire, gas, ash, etc. Physicality will alter the properties of the stuff such that it condenses itself and becomes exceedingly heavy. Viscous, too, if not outright solid. Binding is used to augment this and to prevent it from moving altogether.
-An aether system which prevents buildup via some sustainable means. Fold it into the aether if that's safe and secure, or just toss it into a useless world nobody cares about. Include a summoning outgrowth which actually extends into the portal and calls heat and excess material back from whence it came.
-A healing and binding system which aims to slowly repair the big hole in reality. Not the whole thing at once, just try and make something which will slowly wear it down at the edges.
Security stuff:
-A luck system which decreases the likelihood of system failure and/or other calamities from the plane of fire in the future.
-Use aether, physicality, summoning, healing and binding affinities to make a physical anti-tampering shell (which should also act as a last line of defense if the magma is too much for the containment systems to handle). Let's go with summoned adamantine, melded together and made as durable as possible by physicality. Aether affinity is used to counteract magical interference or attacks, and healing will ideally make it repair itself if by some miracle there is a breach.
-A knowledge system which coordinates the various other systems, plus sends out alerts on the council video channel if something goes wacky.