Offense:
Spam Fleche and Flaming Whip alternatively.
Essence of Sharpness, Glaciation, Scorch and Charcoal will be your DPS.
Defense:
Heal on kill from Fleche.
Barrier from Rigidity.
Shield from Frostbite.
Lifesteal from Clemency.
Shield (and maybe Heal) from Ice Shield.
Heal on attack from Voracity.
HP regen from Regeneration.
While also increasing your HP from Essence of Frost.
Guide:
Level up Astrid's Masterpiece until 0.5s cooldown reset.
Don't level up Memories. Just buy higher versions.
Level up essences instead.