Blue Mage

You are one of a rare order of wizards capable of learning their enemies abilities just by observing them. They are able to manipulate their magics to do things that were only thought capable by monsters.

Blue Mage Spellbook

2nd-level Blue Mage feature

Using specially prepared inks and ancient incantations passed down by your wizardly order, you have awakened an arcane sentience within your spellbook.

While you are holding the book, it grants you the following benefits:

• You can use the book as a spellcasting focus for your wizard spells.
• You can observe and write in abilities that you see your enemies use. Whenever an enemy uses a non weapon action (including spells) you can attempt to learn the ability used by performing an Intelligence (Arcana) check. The DC is 12 + the CR of the enemy, rounding up. If you succeed you add the action to your Spellbook. If that action was a spell, you add it to your spellbook as if you had added it as normal. If it is an action, you add it but the "level" of the ability is equal to half of the monster's CR, rounded down

Observe Abilities

6th-level Blue Mage feature

 You can now use your observation to spot passive abilities of enemies. The check is still the same and you can write them into your spellbook the same way you would actions including giving them a level.

At the end of a Long Rest, you may spend a spell slot of the corresponding level to apply a passive ability to yourself until the end of your next Long Rest.

Adaptive Resistance

10th-level Blue Mage feature

Once per Long Rest, you can acquire one Resistance or Immunity an enemy has until the end of your next Long Rest.

Legendary Observation

14th-level Blue Mage feature

Your connection to your Blue Mage Spellbook has become so profound that your soul has become entwined with it. While the book is on your person, you have advantage on all Intelligence (Arcana) checks, as the spellbook helps you remember magical lore.

In addition, you can now try to observe Legendary Actions.