Magic Resistance. The Zaphiel has advantage on saving throws against spells and other magical effects.

Cursed Blood. Blood flowing in Zaphiel is a pure curse. Upon taking slashing, piercing damage creature that dealt this damage in 5ft range get's a random curse. 

Angel of knowledge. Zaphiel knows name of every creature he sees, and can't forget anything he learned.

Bloody runes. Casting curses or hexes doesn't cost Zaphiel any spell slots and his body serves as arcane focus.

Even in lie i tell the truth. Only by Detect Thoughts someone can tell if Zaphiel is telling a truth.

Spellcasting. Zaphiel spellcasting ability is Intelligence (spell save DC 19, +11 to hit with spell attacks). The Zaphiel can cast identify and suggestion at will and has the following wizard spells prepared:

Cantrips (at will): fire bolt, light, mage hand, prestidigitation, shocking grasp

1st level (4 slots): silvery barbs, shield, mage armor, magic missile

2nd level (3 slots): detect thoughts, mirror image, misty step

3rd level (3 slots): counterspell, bestow curse, vampiric touch

4th level (3 slots): banishment, wall of fire, confusion

5th level (3 slots): legend lore, modify memory, bigby's hand

6th level (1 slot): chain lightning

7th level (1 slot): divine word

Multiattack. Zaphiel makes two attacks with his cursed hand, or cast spell and one cursed hand attack.

Cursed hand. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) necrotic damage, or additional (1d8 ) necrotic damage if target is cursed, additionaly heals for half the damage if target cursed. 

I know that thing too. Zaphiel upon seeing someone using his ability such as class feature, he can use his reaction, to copy that ability. He can only have one ability from this reaction at the time.