School of Fiends

School of fiends allows the wizard to focus on demology and demonic summoning. Fight evil with evil.

Student of Demonic Lore

At 2nd level, your studies of fiends and their history grant you a better grasp of the languages they speak. You gain proficiency in the Abyssal and Infernal languages, if you did not already know them.

Additionally, whenever you make an Intelligence check related to demons, devils, or other demonic knowledge, you can add twice your proficiency bonus, instead of any proficiency bonus you normally apply.

Demonic Servant

At 2nd level, you make your first successful attempt at placing an extra planar creature under your control. You add the find familiar spell to your spellbook if it is not there already. When you cast find familiar, you can choose an imp or quasit as your familiar.

Additionally, you can use your bonus action, to allow your familiar to make one Attack.

In combat, the familiar shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take another action. That action can be one in its stat block or some other action. If you are incapacitated, the familiar can take any action of its choice, not just Dodge.

Powerful Binding

Starting at 6th level, you add the summon lesser demons to your spell book if it is not there already. when you cast summon lesser demons or greater demons, you may choose weather to summon demons or devils and what D6 it will be. fiends of CR 1 or less that you summon are friendly to you, and will obey your commands.

whenever you summon a fiend the following applies: 

- They add your proficiency bonus to their attack rolls and damage rolls.

- Their natural attacks are consider magical if they aren't already.

- They add your wizard level to their maximum health.

Fiendish Being

At 10th level, you have become accustomed dealing with fiendish beings and how to deal with them. Dealings with demons and devils make you resemble some of their traits. Such as having a brimstone smell or forked tongue. Scales and skin pigment changes may occur. Likewise you do gain the following features:

You gain resistance to cold damage, fire damage and poison damage.
You have advantage on saving throws against being poisoned.

When you summon a fiend with a CR equal to your wizard level or lower,  the fiend will consider you friendly and will obey your commands.

Master of the Infernal

Starting at 14th level, your experience with demonic forces has taught you how fiends think and, more importantly, what they fear. Your sheer force of will can be enough to crush the fiend’s resistance to your control.

You can use magic to bring fiends under your control, even those created by other wizards. As an action, you can choose one fiend that you can see within 60 feet of you. That creature must make a Wisdom saving throw against your wizard spell save DC. If it succeeds, you can't use this feature on it again for the next 24 hours. If it fails, it becomes friendly to you and obeys your commands until you use this feature again.

Powerful fiends are harder to control in this way. If the target is a arch devil or a demon lord, it has advantage on the saving throw. If it fails the saving throw it can repeat the saving throw at the end of every hour until it succeeds and breaks free.

Once you use this ability you cannot use it again until the next long rest.