•Ki cost for elemental disciplines is divided by 2 for even numbers and reduced by 2 for odd numbers.
•Reducing the levels you can get the elemental disciplines 6 to 3, 11 to 6, 17 to 11.
-Getting elemental adept feat at level 3 and making WIS your spell casting ability. You are resistant to one elemental type of damage.
-At level 6, while making damage with unarmed strike/monk weapon, you add 1d4 of elemental type damage.
-At level 11, you can create as a bonus action, an elemental weapon and it counts as a monk weapon. Damage is the weapon style damage (like slashing for sword) + the elemental type from level 6. Plus, once a day, you roll 2d6, and when you deal elemental damage, you can add one of the rolls to the damage. It becomes d8 in level 17.
-At level 17, all your elemental damage is causing creatures with immunity to the elemental type act like it's resistance. Your resistance to the one elemental type damage from level 3 becomes an immunity. You absorb power from other sources up tp 30 feet from you for your elemental immunity, and gain one hit point from it. (For example, if you are immune to fire damage, and a wizard casted fireball and there is fire 30 feet from you, you gain 1 hit point.)
Its not op. Monks are underpowered and the designers seem to deliberately make them that way, so i think it brings them to where they need to be with a few tweeks.
I would not reduce the level that you get the disciplines at but i would allow access to more disciplines. Start with 3 or 4 and get another 2 at each of 6th, 11th, and 17th level with swap outs allowed at each of those levels.
Ki cost reduction for spells is fine. I use 1 ki for a 1st or 2nd level spell, 2ki for a 3rd or 4th level spell and 3ki for a 4th or 5th level spell. However at higher levels there is potential for imbalance. Using this for instance An 18th level monk could cast cone of cold 6x per short rest. No full spellcaster could do that, so puting a cap on the number of spells you can cast per spell level helps balance it out. 4, 3, 3, 3, 2.
Dont forget upcasting. 1 ki point per 2 spell levels, max 5th level
3rd level - Elemental adept feat and resistance to one element is fine. Its a bit early in the game to get a permanent resistance but i dont think its really a big deal. Since it is a four elements monk maybe add something like a 1st level absorb elements spell once per short rest or proficiency bonus per long rest. Should a four elements monk not be able to resist any of the four elements? Food for thought.
6th level - Adding d4 elemental type to unarmed strikes/weapon is cool and thematic. I think monks need a bit more damage in melee so i thinks it is balanced.
11th level - Creating elemental weapon - is this like the spell flame blade where the entire weapon is the element? Also cool and thematic. Can you add the d4 elemental damage from the 6th level ability to this as well? 2d6 once per day and picking the better die is fine although i think once per short rest would also be okay. As a suggestion you could also add the elemental weapon spell to the spell list. It would be 2 ki points to cast and spend one 1ki point for a 2 level upcast at 13th level and 1 more ki for another two level upcast again at 17th level. This would help the monks damage scale a bit better. The monk damage from level 11-20 is notoriously bad. If you did this though i would not do the 2d6 thing.
17th level - a big no to overcoming immunity to elemental damage. Doing fire damage to a fire elemental? Its made of fire. See if you can figure something else instead of this. For the monk, Immunity to one element is fine. I think forge cleric gets that too at 17th level. Healing one hit point at this level seems not worth the action (or reaction?) that would be required to do it. Even if it does not require any action it still seems too weak for this level.
•Ki cost for elemental disciplines is divided by 2 for even numbers and reduced by 2 for odd numbers.
•Reducing the levels you can get the elemental disciplines 6 to 3, 11 to 6, 17 to 11.
-Getting elemental adept feat at level 3 and making WIS your spell casting ability. You are resistant to one elemental type of damage.
-At level 6, while making damage with unarmed strike/monk weapon, you add 1d4 of elemental type damage.
-At level 11, you can create as a bonus action, an elemental weapon and it counts as a monk weapon. Damage is the weapon style damage (like slashing for sword) + the elemental type from level 6. Plus, once a day, you roll 2d6, and when you deal elemental damage, you can add one of the rolls to the damage. It becomes d8 in level 17.
-At level 17, all your elemental damage is causing creatures with immunity to the elemental type act like it's resistance. Your resistance to the one elemental type damage from level 3 becomes an immunity. You absorb power from other sources up tp 30 feet from you for your elemental immunity, and gain one hit point from it. (For example, if you are immune to fire damage, and a wizard casted fireball and there is fire 30 feet from you, you gain 1 hit point.)
I know it's a strong subclass, but is it op?
Its not op. Monks are underpowered and the designers seem to deliberately make them that way, so i think it brings them to where they need to be with a few tweeks.
I would not reduce the level that you get the disciplines at but i would allow access to more disciplines. Start with 3 or 4 and get another 2 at each of 6th, 11th, and 17th level with swap outs allowed at each of those levels.
Ki cost reduction for spells is fine. I use 1 ki for a 1st or 2nd level spell, 2ki for a 3rd or 4th level spell and 3ki for a 4th or 5th level spell. However at higher levels there is potential for imbalance. Using this for instance An 18th level monk could cast cone of cold 6x per short rest. No full spellcaster could do that, so puting a cap on the number of spells you can cast per spell level helps balance it out. 4, 3, 3, 3, 2.
Dont forget upcasting. 1 ki point per 2 spell levels, max 5th level
3rd level - Elemental adept feat and resistance to one element is fine. Its a bit early in the game to get a permanent resistance but i dont think its really a big deal. Since it is a four elements monk maybe add something like a 1st level absorb elements spell once per short rest or proficiency bonus per long rest. Should a four elements monk not be able to resist any of the four elements? Food for thought.
6th level - Adding d4 elemental type to unarmed strikes/weapon is cool and thematic. I think monks need a bit more damage in melee so i thinks it is balanced.
11th level - Creating elemental weapon - is this like the spell flame blade where the entire weapon is the element? Also cool and thematic. Can you add the d4 elemental damage from the 6th level ability to this as well? 2d6 once per day and picking the better die is fine although i think once per short rest would also be okay. As a suggestion you could also add the elemental weapon spell to the spell list. It would be 2 ki points to cast and spend one 1ki point for a 2 level upcast at 13th level and 1 more ki for another two level upcast again at 17th level. This would help the monks damage scale a bit better. The monk damage from level 11-20 is notoriously bad. If you did this though i would not do the 2d6 thing.
17th level - a big no to overcoming immunity to elemental damage. Doing fire damage to a fire elemental? Its made of fire. See if you can figure something else instead of this. For the monk, Immunity to one element is fine. I think forge cleric gets that too at 17th level. Healing one hit point at this level seems not worth the action (or reaction?) that would be required to do it. Even if it does not require any action it still seems too weak for this level.