so I'm using the create a monster thing on here for my big bad of my Bard Quest campaign and I am not sure what to classify her as? She's an Eladrin, noble bard. so would she be fey or humanoid?

also i want her legendary action to be a "Talent Thief" thing cause on the story aspect, she basically steals the talent of other bards to boost her own magic but idk how to make that work mechanically.

Eladrin can be humanoid or fey.  Read about it in Mordenkainen's Tome of Foes or just use whichever feels right. 

Talent Thief.  [Name] chooses a creature she can see within 60 feet of herself.  That creature must make a DC [8 + proficiency bonus + ability score modifier] Wisdom saving throw.  On a failure, the target loses one skill or tool proficiency of [Name]'s choice and [Name] gains that proficiency. If [Name] is already proficient in it, her proficiency bonus is instead doubled for checks she makes with it. 

The target doesn't know that it lost the proficiency until it tries to use it. 

This effect lasts until the target finishes a long rest. 

Insert the appropriate names and numbers and rewrite the bits I got wrong. 

In 5e, most eladrin are humanoids and live in the Feywild, but some of them have transformed back into fey creatures because of the Feywild's magic. These fey eladrin are allowed back into Arvandor, the primal elves' original home and where the elf deities dwell.

If you make her humanoid, she'll be susceptible to spells like Hold Person and Dominate Person, so she might be one bad saving throw away from being beaten unless you also give her Legendary Resistance. If she's fey, she'll be affected by spells like Protection From Evil And Good, Magic Circle and Hallow, an oath of the ancients paladin's Channel Divinity: Turn the Faithless or an arcana domain cleric's Channel Divinity: Arcane Abjuration.

Your "Talent Thief" idea sounds similar to the Arcane Trickster's Spell Thief class feature. You should take a look at that and see if you can adapt it to your needs.