How about a barbarian that fights demons?
Path of the Fallen
Learn from your Enemy
Starting when you choose this path at 3rd level, you gain the resistances of your foes when you rage. While raging you gain resistance to cold, fire, poison, bludgeoning, piercing, and slashing from nonmagical attacks that aren’t silvered.
Beginning at 6th level, your rage frightens those are are not used to it. Any creature you choose that starts it turn or enters within 30 feet of you while you are raging must make a Wisdom saving throw. On a failure, On a failed save, the creature is frightened until the start of its next turn. If a creature’s saving throw is successful, the creature is immune to your fear aura for the next 24 hours..
Beginning at 10th level, your rage flows into your weapons and your very soul. You gain advantage on all saving throws against magical effects and spells while raging. Your weapon counts as a +1 version of itself while you are raging. If your weapon has a better enchantment that +1, use that instead.
Starting at 14th level, when you rage, you take on the visage of a devil. You gain immunity to all nonmagical weapons, immunity to poison and fire damage and the poisoned condition, giant bat wings that grant you a fly speed of 60 feet per round, and truesight out to 60 feet while raging.
Demons and Devils are about to be the new hotness in DnD, so let’s build characters that can hurt them back!
You are part fiend, so you know what hurts and how to hurt others. You gain the ability to gain advantage on attack rolls against fiends twice. This ability refreshes after a short rest.
Ring of Life
Ring, rare, very rare, legendary (requires attunement)
This twisted vine ring provides you with extra life each day. You gain a 25(rare), 50(very rare), or 75 (legendary) temporary hit-points at dawn each day.
You’ve run so long among the beasts of the field, you have learned how to really run among them. You now know how to become the beast of the field and use that to stalk your prey!
Beast of the Field
At 3rd level, you can use your action to magically assume the shape of a beast that you have seen before. You can use this feature twice. You regain expended uses when you finish a short or long rest.
Your ranger level determines the beasts you can transform into, as shown in Table: Beast Shapes. At 3rd level, for example, you can transform into any beast that has a challenge rating of 1/2 or lower that doesn’t have a flying or swimming speed.
Table: Beast Shapes
||No flying or swimming speed
||No flying speed
||you can now become magical beasts
You can stay in a beast shape for a number of hours equal to half your ranger level (rounded down). You then revert to your normal form unless you expend another use of this feature. You can revert to your normal form earlier by using a bonus action on your turn. You automatically revert if you fall unconscious, drop to 0 hit points, or die.
While you are transformed, the following rules apply:
- Your game statistics are replaced by the statistics of the beast, but you retain your alignment, personality, and Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature’s bonus instead of yours. If the creature has any legendary or lair actions, you can’t use them.
- When you transform, you assume the beast’s hit points and Hit Dice. When you revert to your normal form, you return to the number of hit points you had before you transformed. However, if you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form. For example, if you take 10 damage in animal form and have only 1 hit point left, you revert and take 9 damage. As long as the excess damage doesn’t reduce your normal form to 0 hit points, you aren’t knocked unconscious.
- You can’t cast spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your beast form. Transforming doesn’t break your concentration on a spell you’ve already cast, however, or prevent you from taking actions that are part of a spell, such as hunters mark, that you’ve already cast.
- You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can’t use any of your special senses, such as darkvision, unless your new form also has that sense.
- You choose whether your equipment falls to the ground in your space, merges into your new form, or is worn by it. Worn equipment functions as normal, but the GM decides whether it is practical for the new form to wear a piece of equipment, based on the creature’s shape and size. Your equipment doesn’t change size or shape to match the new form, and any equipment that the new form can’t wear must either fall to the ground or merge with it. Equipment that merges with the form has no effect until you leave the form.
At 7th level, you also add your proficiency bonus as a bonus to the AC of the creature you have changed into in addition to its normal AC bonuses. You can still add the AC bonus of any armor you are wearing to your AC as well.
Beast body, Human Tactics
At 11th level, you add your proficiency to your attack and damage rolls for the shape you are in in addition to the normal attack and damage bonuses the shape has.
Master of the Field
At 15th level, you gain the ability to become a beast, magical beast, or elemental of up to CR 5.
Some love for the fighter today with a new fighting style.
You gain an extra reaction each round.
How about some alternative features for the monk?
Ki Force Strike
Starting at 5th level, you can hit a foe with your ki. You can spend 1 ki point to attempt to strike a foe within 100 feet with a melee strike. You may make multiple attacks in a round at range each round by spending a ki point for each strike.