Since the majority of all my incantations involve the spell caster requesting a power involving a verb, I am curious if I should always use the infinitive of the verb or if I should always us the future passive participle of the verb as you have done translating to shape into formandi
The
Formandi I have used here is actually
not a
future passive participle (which grammatically behaves as an adjective, and is commonly reffered to as the gerundive).
Formandi here is a
gerund, that is when you treat a verb as a noun, and decline it in cases (only singular forms, no switching between grammatical genders). Here it is in the genitive, as the "act of shaping" belongs to "power" - ergo "the power of shaping". The gerund has dative, accusative and ablative forms as well. The nominative gerund would simply be the infinitive used as a noun in a sentence.
If you take a look at the verb
Formo "form" here, and click "more" on conjugation, you find the gerund forms at the bottom. Note that dative and ablative gerunds always are identical, though their meaning is different.
https://en.wiktionary.org/wiki/formo#Latin
Therefore you would never use the infinitive (audire) in such a construction as you have there, although that appears to be the most literal way of translating it from English. You would rather use
Audiendi, or phrase it in another way.
extra terminos hominis is correct. You're getting hang of it
I have two more things to add:
1 - If the imperative
Da is directed at more than one person/entity or what it is (the
Parcae?), it should be the
plural imperative,
Date. This does not change anything else in the phrase/sentence.
2- You might find this more helpful than my less than perfect attempt at explaining gerunds and gerundives:
http://www.thelatinlibrary.com/101/GerundGerundive.pdf
or
http://homepage.usask.ca/~jrp638/latin/RLsheets/5Dgerundive.pdf
There are also videos on Youtube that explain the basics Latin grammar. Just search for "Latin gerundive", "Latin ablative", etc.
Not that we won't gladly help you with all this, but it's helpful to get things explained in different ways. Especially if you are not very familiar with all the grammatical terms.