Vortigern's Focus

Vortigern's Focus allows the caster to make concentration on ONE spell autonomic, allowing the caster to engage in additional actions, including casting other spells, without needing to make a concentration roll.  Vortigern's Focus must be cast at a higher spell level than the spell affected.

Vortigern's Focus only works on spells that create a static condition, such as Invisibility or Anti-Magic Circle.  
It will not work on spells that require the caster's continual focus (Bigby's Hand), judgement ("each round, creatures of your choice"), or attention (such as Beast Bond, or detection spells), it is likewise ineffective on spells that require continuing attack rolls, or allow the caster to move the spell location from round to round.