Divided Mind

A way to concentrate on two spells at once is one of the first things every DM learns not to homebrew.

The reason is that it opens up far too many abuse cases… 

So... this is a bit op. Concentration exists for a reason, couple that with ability score increases and a proficiency is to much. Its a cool concept but here is what I would do, add more prerequisites. IE only wizards (no multi class could use this). You could add some flavoring of they have read so much that they have more mental capacity, I also think that u should add some drawbacks to multi concentrating. 1 every roll is at dis advantage, The potency of the spell is weakened (up to the dms description) and spells over 5th level cannot utilize this feat (bc they are so advanced). This still makes this a powerful and flavorful feat but allows it to feel like you sacrifice something for it instead of just being able to play 2 spellslingers at a time.

Quote from JBomb679 >>

So... this is a bit op. Concentration exists for a reason, couple that with ability score increases and a proficiency is to much. Its a cool concept but here is what I would do, add more prerequisites. IE only wizards (no multi class could use this). You could add some flavoring of they have read so much that they have more mental capacity, I also think that u should add some drawbacks to multi concentrating. 1 every roll is at dis advantage, The potency of the spell is weakened (up to the dms description) and spells over 5th level cannot utilize this feat (bc they are so advanced). This still makes this a powerful and flavorful feat but allows it to feel like you sacrifice something for it instead of just being able to play 2 spellslingers at a time.

Agreed. It's too much to allow PCs to concentrate on multiple spells (although I find this to be a very fun ability to give to enemy spellcasters bosses!) without some sort of drawback. The way I would fix it is the following:

• Remove everything except the double concentration ability
• Extend it to read, "you cannot concentrate on two spells if either is 6th level or higher, or if they are of the same school of magic." (Last part mostly to deal with way too many summons, and simultaneously prevents concentrating on multiple of the same spell.) "While concentrating on two spells, you have disadvantage on saving throws made to maintain concentration, and casting another levelled spell instantly ends your concentration." (This seems like a very brutal nerf, but double concentration is SUPER overpowered, allowing for a lot of ridiculous combos - even just Blur + Mirror Image [ + Mage Armour + Shield] is insanely strong - so limiting other options is vital.) "In addition, while you are concentrating on two spells, you must make a DC 15 Intelligence saving throw at the start of each of your turns. The DC of this saving throw increases by 1 for each round during which you continue to concentrate on both spells. On a failure, you lose concentration on one of the spells of your choice." (This is to prevent concentrating for extended periods of time on long-lasting buffs or debuffs.)
• Extend the prerequisite to require, "an Intelligence score of 17 or higher, a full spell-casting class of 8th level or higher, and not a Warlock."

Final Feat

Divided Mind
Prerequisite: An Intelligence score of 17 or higher, a full spell-casting class of 8th level or higher, and not a Warlock

Your studies into the nature of the mind have unlocked a new degree of focus for your brain. You can maintain concentration on two different spells at the same time, as long as neither is of 6th level or higher, and they are of different schools of magic. While maintaining concentration on two spells, you have disadvantage on saving throws made to maintain concentration, and casting another spell of 1st level or higher instantly ends your concentration. In addition, while concentrating on two spells, you must make a DC 15 Intelligence saving throw at the start of each of your turns. The DC of this saving throw increases by 1 for each round you continue to concentrate on both spells (to a maximum of 30) and resets to 15 when your concentration on either spell ends. On a failure, you lose concentration on one of the spells of your choice.

Still very strong, but feels much better balanced now to me. Feel free to criticise or add suggestions :)

It's already op even if you remove the perception proficiency

Quote from divinedomain >> 

Divided Mind
Prerequisite: An Intelligence score of 17 or higher, a full spell-casting class of 8th level or higher, and not a Warlock

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 Your studies into the nature of the mind have unlocked a new degree of focus for your brain. You can maintain concentration on two different spells at the same time, as long as neither is of 6th level or higher, and they are of different schools of magic. While maintaining concentration on two spells, you have disadvantage on saving throws made to maintain concentration, and casting another spell of 1st level or higher instantly ends your concentration. In addition, while concentrating on two spells, you must make a DC 15 Intelligence saving throw at the start of each of your turns. The DC of this saving throw increases by 1 for each round you continue to concentrate on both spells (to a maximum of 30) and resets to 15 when your concentration on either spell ends. On a failure, you lose concentration on one of the spells of your choice.

 Seems pretty good! Balancing the ability to concentrate on two spells at once is pretty difficult, and this seems like a fair compromise for doing such.

nah man this is goated