For my clarity, may someone list the advantages that a Verditius magus has in creating Talismans and charged items?
For talismans, they may use the "Verditius runes" to the Talisman attunement? (I know it is a silly question...)
ps: the bonus of the talisman attunement is of any use in a certamen?
If the answer is "no", what do you think of it as house rules (tha image on page 25 of Gotf has inspired me)
Verditi have three advantages when creating magic items of any type (including charged items and talismans):
First, if they create the item that they wish to enchant from raw materials themselves, they may add their craft score to their lab total when enchanting the item.
Second, when a verditius creates an item for enchantment they can work verditius runes into the item and receive a bonus equal to their philosophae score to their lab total. The total of this bonus and form and material bonuses can not be greater than the magus' magic theory score. In my experience it is possible more often than not to get shape and material bonuses for an item that are equal to the magus' magic theory score with no philospae included. the primary benefit of this ability is to be able to get a verditus runes + shape and material bonus equal to the character's magic theory on an item that the character creates thus allowing the character to create items with their available craft skill without missing out on form and material bonuses that can't be accessed by their particular craft. For example; a typical mage might make a weather controlling device out of a wand of oak that had been killed by lightning. A verditus jeweler might instill the same effects in a necklace that includes representations of these elements (lightning, oak, and etcetera). The non-verditius would rake in a pile of form and material bonuses,. The verditius would rake in a similar sized pile of verditious runes bonuses instead, and they would also add their craft skill.
Third, when opening an item that they have created for enchantment the cast of opening the item is reduced by a number of pawns equal to their craft skill (to a minimum of one pawn).
PS. from page 98 "Bonuses from attunements...apply to totals to cast ritual, formulaic, and spontaneous magic, but they do not apply to magic resistance or any laboratory activity...â€ from this I'd say maybe, if your talisman has an applicable attunement to the certamen I'd probably say yes but this would be a story guide judgment call rather than anything that one could reasonably infer from the rules.
Verditius Runes... mmmm...
1 A Talisman may be attuned to give a bonus based on the materials and form of the Talisman.
2 A Verditius may give a bonus up to Ph. score (with a cap of MT) instead of the material and shape bonus.
3 Question: may a Verditius attune a Talisman on the V runes to give a general bonus up to their Ph. score?
I don't personally think that there's any justification for that. Talisman attunements are specificly pointed out as shape and material bonuses and verditius runes aren't actually specific. They're a flat bonus based on the phiosophae score of the magus.
So if you wanted to include that in your game you'd need to find a way to limit the runes to the specific bonuses that the magus wants (I think anyone would agree that a flat bonus to all spellcasting equal to the creator's philosophae score would be excessive).
I would advisse you to force the players to find ingenious ways to incorporate different shapes and materials into their talisman rather than avoid the issue by iinventing a verditius runes bonus.
I'd also advise (not that I'm any great authority) that you not limit yourself to the form and effect bonuses in the fifth ed. book but instead use them as examples to create your own.