Doomsayer

The magic you seek is as powerful as it is destructive.
Arcane Specialty
Any fool can learn to hurl a Fireball, but only a Master of the apocalypse can open a Black Hole. Some doomsayers use their terrible power to amass a conquering army; others seek to become a force of Darkness and to reshape the world according to their own vision.
Apocalypse Savant
Beginning when you select this specialty at 2nd Level, the gold and time you must spend to copy an apocalypse spell into Your Spellbook is halved.
Wicked Presence
At 2nd Level, you gain the ability to instill a sense of impending doom in creatures who witness your power. When you kill a creature with a spell that isn’t a cantrip, you can use a Bonus Action to select one or more creatures within 30 feet of the creature you just killed. Each of those creatures must make a successful Wisdom saving throw or become Frightened of you for 1 minute. A Frightened creature can repeat the saving throw at the end of each of its turns, Ending the Effect on itself on a success.
Once you use this feature, you can’t use it again until you finish a Long Rest.
Terrible Power
Starting at 6th level, whenever you score a critical hit with a spell Attack, choose one of the following two effects:

• Every creature affected by the spell must make a successful Wisdom saving throw or become Frightened of you until the end of its next turn.
• Every creature affected by the spell must make a successful Constitution saving throw or become Poisoned until the end of its next turn.

Merciless Onslaught
Starting at 10th level, you have advantage when making spell Attack Rolls against creatures that are Frightened or Poisoned.
Power from Darkness
Beginning at 14th level, your spell attacks score Critical Hits when the Attack roll is a natural 19 or 20.