So it seems to me that with this combination you can effectively persist (change the duration of a spell to 24 hours) any spell (with target: personal) on any character in a collective.
So lets say we have a tactician 10/thrallherd 10 with a wizard and cleric cohort. Each of those cohorts has a ring of continuation (Ultimate Equipment pg.168) which reads:
This band of braided copper wires throbs ever so slightly in
harmony with its wearer’s heartbeat. Whenever the wearer
of this ring casts a spell with a range of personal, that spell
remains in effect for 24 hours or until the wearer casts another
spell with a range of personal (whichever comes first). Spells
that usually only affect one specific action (such as making a
particular attack) are expended after that action. This does not
reduce the duration of spells that normally last longer than
24 hours. Casting a new spell does not eliminate a previous
spell if its normal duration is such that it would still be in
effect. However, attempts to dispel or otherwise eliminate a
spell kept active by the ring work normally and, if successful,
remove the spell from the ring, causing the wearer to lose all
benefits from that spell.
Now the tactician (Psionics Unleashed pg. I don't know I'm getting my info off the website, but its a base class and pretty easy to find) has a nice little broken ability called Echo Effect, which states:
Echo Effect (Su)
At 8th level, the tactician gains the ability to copy non-permanent magicial and psionic effects within his collective. If a member of the collective is affected by a magicial or psionic effect with a duration greater than 1 round, the tactician can echo it onto another member of his collective. To do so the tactician must first identify the power properly (see the Spellcraft skill description).
Echoing a magical or psionic effect is a standard action that provokes attacks of opportunity and costs the tactician a number of power points equal to the original effect's caster of manifester level (whichever applies). As a supernatural ability, a tactician is permitted to spend more power points than his manifest level on this effect. The new target must be legal for the effect in question (for instance, if you attempt to echo an unaugmented Empathic Connection on a dog, the echo will fail). If the effect allows a saving throw, the new target is entitled to a saving throw when the effect is echoed (same DC as the original power).
Only the basic effect and augmentation are echoed: metamagic and metapsionic feats do not echo. The echo has all the same decisions made as the original. For example, Specified Energy Adaption echoes would guard against the same energy type, while a 5pp Empathic Connection (extended duration) could not be echoed as a 5pp Empathic Connection (affects aberrations). The echo takes effect at the same caster or manifester level as the originator. When the original ends or leaves the collective, all echoes of it also end. An echo can be dispelled as normal without terminating the original.
A tactician can spend power points to augment this supernatural ability. For every 4 additional power points spent, the echo may reach an additional target. If the augment would raise the cost of the echo above the tactician's manifester level, the echo attempt fail (although he may still attempt to echo it onto a single target). The tactician knows if an effect is beyond his ability to echo this way when he identifies it.
Now, if I am understanding this correctly, which I may not be, it seems like any spell (with range: personal) the cleric or wizard casts on themselves will be converted into a duration of 24 hours. The tactician should then be able to use his Echo Effect ability to then grant the spell to himself, while its duration remains at 24 hours. Since the ability Echo Effect seems to copy the spell/ability as it is in that moment, and in that moment, due to the ring, its duration is 24 hours, the ability should also copy the spell to himself (or any other member of his collective) with its duration at 24 hours regardless of whether he has a ring or not.
Since the ring overrides the previous spell but that ring is not present on the tactician it seems to me that you could just repeat this effect with the cleric/wizard casting a new spell on themselves, having the ring change the duration, and then using echo effect to copy the spell with its new changed duration to the tactician. In this manner the tactician (or anyone else in his collective) can not only gain the effects of any personal spell cast by the buffer thralls but benefit from these spells 24/7 since the ring is no longer maintaining the duration of the spell; the tactician is only limited by his own power point reserve.
