Spell That allows Share spells like effect

[Gideon Marsh]

For an upcoming character who will have a servant not fully under their control I was looking into researching a spell that allows one to share self range spells with an ally, only a rough draft, as will quickly become evident

[insert name here]
school (enchantment or transmutation)
level: Wizard ?
cast time: 1 min
component: V, S, M(?)
duration: min/hour lvl?

For the duration of the spell the target gains the share spell ability as a familiar, allowing you to cast spells with a range of self on the target as a touch spell and allowing you to target them with spells even if they don't affect that creature's type.

The name will come with time and is the least important part, but what of the level and duration, what would be reasonable for these two things. The DM left the decision to me and then running it by him, but I don't want any others who see the spell to exploit the spell too much, as they will be fighting similarly

(for those of you who are curious and may be thinking about it, this was based off of Fate/zero, and I am looking for a way to buff my servant with more than just enlarge person)

[Timebomb]

Going loosely off of Imbue with Spell like Ability, I would say it is a 4th lvl spell with duration of hour/lvl. I would also make it take a focus of something (the servant's catalyst for instance) for flavor mostly. And make the school Evocation (it is weird, I know).

[Gideon Marsh]

Seems reasonable, I can always assume the others would copy me (or try to), but this seems good, My only other important 4th level spell is emergency force sphere, and I hope I don't need that more than once/ day. I'll run it by my DM.