Level 1: Plague Ward
Level 2: Poison Sting / Venomous Gale
Level 3: Plague Ward
Level 4: Venomous Gale / Poison Sting
Level 5: Plague Ward
Level 6: Poison Nova
Level 7: Plague Ward
Level 8: Poison Sting / Venomous Gale
Level 9: Poison Sting / Venomous Gale
Level 10: Poison Sting / Venomous Gale
Level 11: Poison Nova
Level 12: Venomous Gale / Poison Sting
Level 13: Venomous Gale / Poison Sting
Level 14: Venomous Gale / Poison Sting
Level 15: Stats
Level 16: Poison Nova
Level 17+: Stats

Total Cost = 594