As a GM I try to figure out how many Lays the Teleport spell will cross and each one gets a chance at the party. For a long teleport - From Jaiman to Sel Kay - I encourage ritual Magic and some serious meditation - if you have never been to Sel Kay, don't even try it.
A spell off the hip sort of approach, I will let the lays have their say (roll on a chart) and usually completely drain the caster. If the caster has an understanding of the Lays, then I will let the Spell caster a slight chance of navigating. I try to make skills work for the party in this instance. In some instances, I will let a Spell Caster use a Foci to help them resist the nastier part of the Lays effects.
It is my fervent belief that the Spell Casters should have an idea when it is safe or dangerous to cast Teleport spells and to offer or decline on casting one. Depending upon their level the Caster should have some control over the Spell, during all phases of the spells duration.
I have played in games where the GM locked magic right down. After a while you wonder why you are playing a Spell Caster at all.
