Precision

[Floopay]

So, I have actually been writing my own system for quite awhile. My edition has a spell that was originally like "True Strike" in 3.5; but was changed because I have never been a big fan of "True Strike". To make a long story short, I re-stringed the ability to be useful in and out of combat, and adapted it to the 5e spell system.

Let me know if you think this is something that is balanced enough to use in a 5e system

Range Self
Components V, S
Material None
Duration 1 minute
Casting Time 1 action
Level 1st
School Divination
Classes Wizard, Warlock, Sorcerer, Bard, Eldritch Knight

For the duration of the spell, the caster receives a +2 bonus on all proficiency checks, and attack rolls.

Higher Levels At 5th level, this bonus is increased by an additional 1, as well as at 11th and 17th level.

Thanks for reading,
Floopay

[Scorpion_Strike]

The "increase at 5th, 11th, and 17th levels" mechanic usually only applies to cantrips as far as I know; for 1st-level spells and higher, the same effect is achieved through upcasting. For example, you could say that the bonus increases by 1 for every two levels above 1st of the expended spell slot: at 5th level, the caster could expend a 3rd level spell slot for the first time and get a +3 instead of +2 bonus, at 7th level they could get +4, at 11th level they could get +5, and at 17th level they could expend their (only) 9th-level spell slot to get a +6 bonus. The progression would naturally be slower for half-casters, which I think would probably be for the better; many powerful spells require saving throws, so for casters this spell would allow them to be a little more resilient against enemy spells without powering up their own spells reliably, but for martial classes the bonus to attack rolls is going to reliably boost their offensive capabilities as well as they rely more on attack rolls. This is particularly significant since AC and attack bonus are supposed to roughly scale together in 5e, so even a +2 bonus remains pretty relevant through the entire game. Because of that, I would recommend making this a concentration spell, to keep people from stacking this too easily with too many other buffs.

[JNAProductions]

Make it attack rolls only, and Concentration.

Applying to all proficiency checks... That's a +2 bonus to just about EVERYTHING.

[Scorpion_Strike]

Well, the guidance cantrip effectively does the same thing for skill checks and Bless does basically the same thing to three people at 1st level for attack rolls, checks, and saving throws, so I think that a +2 to all those on one target with concentration requirement would be reasonably balanced... I mean, the +1d4 that those other options provide average to a slightly higher bonus on average.

[Ninja_Prawn]

Spoiler: Nitpicks

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Classes Wizard, Warlock, Sorcerer, Bard, Eldritch Knight

EKs don't get access to divinations as part of their 'standard' lists.

a +2 bonus on all proficiency checks, and attack rolls.

'Proficiency check' isn't defined as a term; the closest thing is 'ability check that you apply your proficiency bonus to'.

Higher Levels At 5th level, this bonus is increased by an additional 1, as well as at 11th and 17th level.

Scorpion_Strike is correct, this language applies to cantrips only.

But overall, I'd say this spell is redundant. It's like a weaker version of Bless combined with a weaker version of Guidance (weaker because it can only target Self and the bonus is smaller). The may be a handful of corner cases where this is a better choice than one of those two, but by and large it's outclassed and doesn't have enough of a niche. You might say combining the two benefits into one action is better action economy, but I'd argue it isn't powerful in this case, because you're only likely to need one of the benefits at any given time.

Besides, adding in lots of fiddly +Xs doesn't jive at all with the overall 5e design philosophy, for several reasons.