Haeravon battles the Royal Griffin during the quest "The Beast of White Orchard" on Death March difficulty in The Witcher 3!
Make use of the Quen sign to protect yourself from damage, wait for an opening (or a full stamina bar so you can reapply Quen), perform a strong attack, roll away, repeat. You'll want to make use of the Viper Silver Sword to inflict poison damage, and perhaps the Tawny Owl potion to speed up stamina regeneration. Repeat until victorious!
- Quen sign (absorbs damage)
- Viper Silver Sword (superior silver sword, applies poison DoT)
- Strong strike
- Roll (don't get greedy, attack and roll, attack when Quen is up and)
- Crossbow (shoot Royal Griffin out of sky, attack while grounded)
- Tawny Owl (increases stamina regen, hence Quen uptime)
Check out the full guide at: http://www.gamerguides.com/witcher3