DotF has a Lesser Telepathic Bond. Is there a better higher level version of that? If not, what would be the appropriate spell level for a 1 day/level duration version of the same spell?
Lesser Telepathic Bond is a 3rd level spell connecting a pair of creatures for 10 min/level per the SRD. Extending this to 1 day/level via the metamagic(lasting spell) makes it a 7th level spell which seems reasonable.
(Alternately, extending the base 5th Telepathic Bond spell's 10 min/level duration to 1 day/level would become a 9th level variant using the same feat AND allows connecting multiple creatures. Since RAW gave the Lesser Telepathic Bond a -2 level adjustment since it only affected two creatures, doing so again makes it a 7th level spell, confirming its a reasonable solution.)
Solitonman's Planar Telepathic Bond variant extends the base 5th level spell's duration to 1 hour/level for a +3 adjustment using the same feat, making it an 8th level spell. However he also wants to boost the range to cross planar boundaries which I'd say is easily worth a least another level making his variant a 9th level spell (or 7th level if he limits it to just connecting two minds using the above justification)
*
http://www.d20srd.org/srd/psionic/spells/telepathicBondLesser.htm
*
http://www.d20srd.org/srd/spells/telepathicBond.htm
Lasting Spell (Metamaqic)
source: Mongoose Ultimate Feats
You can make a spell last for much longer than normal.
Prerequisites: Extend Spell, able to cast 3 level or higher arcane spells.
Benefit: The character can change a spell’s duration to one or more time units higher. The time units are round, 1 minute, 10 minutes, hour, day, week, month, year, decade and century. The first progression uses up a spell slot three levels higher than the spell’s actual level, but the spellcaster may extend it further by using up an extra spell slot for each progression.
For example: alarm is a 1st level spell lasting 2 hours per caster level. A lasting alarm is a 4th level spell lasting 2 days per caster level, and it can be modfied further to last 2 weeks per caster level by using up a 5th level slot.
Spells with a concentration, instantaneous, or permanent duration are not affected by this feat.