Magical Mimicry

Increase your Wisdom and Intelligence by 1 (maximum 20). You must be a Wizard or Artificer to obtain this feat.

Your keen observation and high intelligence allows you to observe unknown spells cast in your presence and cast them yourself, learning the verbal and somatic components and using a spell casting focus. For this feat, "unknown spells" refers specifically to spells you do not have prepared when you observe the spell. You may only have one mimicked spell prepared at a time. If you observe a second spell you wish to mimic, you lose the knowledge of the first spell. If you become unconscious, you lose all knowledge of the spell. When you cast the mimicked spell on the day it is observed, you expend a spell slot of the highest spell slot level you have, regardless of the mimicked spells level with the effects of the spell at that level (i.e., if you cast a 2nd level spell using your 5th level spell slot, the spell is cast at 2nd level even if there is an added effect at higher levels). You cannot use this feat again until you take a short rest.

You must cast the mimicked spell before taking a long rest or the knowledge of the spell is lost. If you spend your long rest copying the knowledge of the wizard spell into your spell book (wizard) or working with your artificer tools (artificer) to duplicate the spell, you permanently gain use of the spell and you may cast it as if you had scribed it, expending a spell slot as appropriate or at the highest level you have for spells beyond your current level (i.e., a 5th level wizard with 3rd level spell slots using Magical Mimicry to scribe 8th level Clone into their spell book--Clone will always be cast at the highest spell slot available until you obtain 8th level spell slots). The time required is 1 hour per spell level and the cost is 25 gp per level (i.e., 1st level spell is 1 hour and 25 gp, 9th level spell is 9 hours and 225 gp). You must remain in contact with your arcane focus or tinkering tools during the scribing and experimentation. At the end of the long rest, roll a d10. On a 1, you gain no benefits of a long rest and you suffer 3 level of exhaustion. On a 2 - 5, you gain the benefits of a short rest but suffer 2 level of exhaustion. On a 6-9, you gain the benefits of a short rest but suffer 1 level of exhaustion. On a 10, you gain the benefits of a long rest.

If the spell is not on your normal spell list (wizard or artificer), in addition to the 1d10 above rolls and results, roll a d20 at the end of the long rest. On a 1, you lose all knowledge of the spell and it is gone from your spell book. On a 2-10, you may cast the spell using your normal spell casting ability but expending a spell slot 1 level higher than the spells normal level (or your maximum level if above your current level) (i.e., for the 1st level spell Bless, a wizard would need to expend a 2nd level spell slot). On a 11 - 17, you may cast the spell using your normal spell casting ability expending a slot on the normal spell level (or your maximum level if above your current level). On an 18-19, you may cast the spell expending a spell slot at one level lower than the normal spell level (no lower than level 1 or at your maximum level if above your current level) (i.e., for the second level spell Augury, a wizard can cast it using a first level slot). On a 20, you may cast the spell as a cantrip (at will) but only 1d4 times per day (rolled at the end of each long rest). Regardless of the roll for the spell at the time of scribing and tinkering, when the wizard or artificer gains their next level, they may cast the spell by expending the normal spell slot level if it is below their highest spell slot level but must use a maximum spell slot level if it is beyond their current maximum spell slot. 

Once you reach 11th level, spells that you observe which are 3rd level spells or lower, you may scribe or tinker one spell on a short rest with no risk of exhaustion and at no cost. In addition, you may have two spells prepared through magical mimicry (observed but not yet cast).  At 17th level, spells that you observe which are 6th level spells or lower, you may scribe or tinker one spell on a short rest with no risk of exhaustion. In addition, you may have three spells prepared through magical mimicry (observed but not yet cast). At 20th level, you have mastered magical mimicry and you may have five spells prepared through magical mimicry (observed but not yet cast) and you may cast those spells as a bonus action regardless of what you do on your action (including other spells). You may scribe any spell of any level on a short rest at no cost up to 2 spells per short rest.