Battle Mage Armor

Sry for being dense but if I have an intelligence of 18 ie +4. so at 5th lvl i would have an AC of 17 + Dex,  at 11th lvl an AC of 21 + Dex and at lvl 17 an AC of  23 or 27 (depending on wether your adding the whole prficiency bonus again) + Dex?

Is that right?

The problem with this spell is how quickly it spirals out of control; I could understand changing the standard Mage Armor 13+ Dex to make it 13 + Int, Wis, or Cha instead - but even still, that is too powerful for lower level spells. The proficiency bonus part isn't clicking with me either - why not have it as proficiency the entire time so that the spell naturally scales? saying it increases by your proficiency bonus and then increases by it again can only be interpreted as adding double your proficiency bonus - which is too strong at any level. It is also my personal belief that a spell should never fully eclipse another at the same or similar level; what I mean by that is, there is no benefit to Mage Armor over this spell - it renders it moot and utterly useless by comparison. My advice, play-test content before you post it; run a short campaign or a small battle where it would normally be used. Because even within abilities capped at 20, this spell could give a Level 5 player a potential AC of 23, 25 with a shield - which this spell does not explicitly prohibit. add in bracers of defense, cloak of protection, ring of protection or the like, and you have someone who can only be hit by the luckiest of rolls or creatures far beyond a reasonable CR.

this ONE!!! is GOOOODDE!!!!!!! use all of time to get strong with AC!!!!!!! (font family)

This would be cool if it was just "AC becomes 13 + DEX + INT" if it was a higher level spell, like maybe 4th level or at least 3rd level, considering that a fighter or a class that can wear medium - heavy armour can reach 20-23 AC at 5th level between Shielf of Faith, plate or half plate, and a shield. Another idea would be to leave it as a 1st level spell and just make it 13 + INT. If you wanted some scaling, you could do sth like "AC increases by 1 point for every level after 1st". Sure, it sounds broken but again for a 5th level spell being able to have 23 AC isn't that bad and anything past that is just a waste of a spell slot. 

I'm not sure why this has such a low rating when the first few pages of every homebrew section it full of entries which can't even come up with a reasonable name.

I love how it has that you need an arcane focus to cast it even though you already need one just to cast spells in general.

Quote from DiceGoblin17 >>

I love how it has that you need an arcane focus to cast it even though you already need one just to cast spells in general.

 You don't need a spellcasting focus to cast spells in general. In fact, using a focus is always optional (except for this spell I guess). Spellcasting foci are used to replace material components (as long as the components have no specified cost and aren't consumed). Spells without material components, as well as spells with only material components that have costs and/or are consumed, have no use for a spellcasting focus. Additionally, even for spells that can benefit from a focus, you are allowed to just acquire the components.

Quote from Keovar >>

I'm not sure why this has such a low rating when the first few pages of every homebrew section it full of entries which can't even come up with a reasonable name.

 Some people (me included) care more about the content of the spell that the quality of the name.