When you cast a spell, from an investet item of course, you have the option of paying two vis to retain the spell in your library after casting it.
Is this also an option when you lose your spell due to another spell's effect (presumable cast by another player)? E.G.: some of the spells that force you to lose an item and discard the spells invested in it.
What about the spells "Aegis of the Sanctum" and "Wizard's Sidestep" which enable you to counter another players spell in his/her round - does this entail casting the Aegis and thus gives you the opportunity to pay two vis to retain it in your library (even if it is not you own action)?