For the duration of the spell, the cost in time and money is cut in half to scribe a single spell into your spell book. This stacks with the Savant abilities to reduce time and cost for spells.   When you succeed in scribing a spell, the Write spell ends.   You can also write a spell into your spellbook that is too high a level for you to cast.

When you do so, roll an Arcana Check.  The DC = 10 + the spell level of the scroll.    If the spell is too high level for you to cast, roll with Disadvantage.  If you fail the check or lose concentration, this occurs:

1. You do not write the spell into your book
2. Your Intelligence is temporarily lowered by 1 point per level of the spell.  Your intelligence returns at a rate of 1 point per day (or a Greater Restoration will return it instantly).
3. You are knocked unconscious for 1 minute per spell level.  You can be woken normally or if you take any damage.

If you exceed the Arcana check by 5 points, you write the spell into your spellbook, you keep the original (allowing you to use the scroll), and the Write spell ends.

If you make the check but do not exceed the Arcana Check by 5 points, you write the spell into your spell book but the original is destroyed, (and the Write spell ends).