I’ll preface this by saying I’ve only played a four elements monk to level 6, so maybe it gets better with late game itemization, though if so, I haven’t seen anyone mention it. But up to level 6, and based on the description of future class features, four elements monk is really in need of a little help. A lot of people have written about this already, but to sum up, the subclass’s core features conflict with the rest of the monk tool kit too much to be useful most of the time. Not only do they compete with core features in the action economy, they also compete in terms of ki. Unless you have a very strong forced movement option that can knock an enemy off a ledge or similar, you’re better off just using the base monk abilities. This is to compare with open hand monk, that gets buffs and passives that directly affect the core skills of the class without costing additional ki. This is always an issue with classes that mesh two different damage dealing skill sets — you can only use one at the same time, but it’s exacerbated on the four elements monk by the fact that the subclass features are typically so underwhelming, limited, and compete for resources with the core features.
We can compare four elements monk to eldritch knight, since both are full martials with limited support casting. In bg3, eldritch knight can get a lot of really powerful spells that support melee, don’t take up resources that affect melee damage and some of which are action economy friendly (shield, misty step). For the reasons described above, four elements monks are far more limited in comparison. On top of that, eldritch knights get cantrips that properly scale and can be used with no resources, while four elements monks “cantrips” have inferior scaling and still cost ki to use.
For four elements monks to be good, they need 1) more forgiving ki costs so they can use both core monk powers and their unique subclass powers, and 2) some way to get around the action economy so they can actually use their subclass powers to support their core skill set.
My recommendation: reduce the ki cost of four elements powers by 1. When a four elements monk uses a monk power or attacks in melee, she can spend one extra ki to use a four elements power as a free action. I think the cantrip style powers should scale properly, and harmony of Fire and Water should also be improved to be more on the level of wholeness of body as well (just make it short rest and usable in combat). If this were done, four elements monk would actually feel strong as a flexible, mixed range striker.
