Arcana Cleric.
The Arcana cleric in SCAG was the best way a character could get an attack cantrip that required a die roll in 2014. Unless your species gave you one, you had to wait until level 4 for Magic Initiate. That one thing is what made the Arcana cleric radically different to play than any other cleric subclass. 2024 cantrips are easier to get, since you can start with them through an origin feat. That's still the main selling point on this subclass.
Being able to roll to hit with a cantrip (and not having the enemy make a save to avoid damage) is a big deal for the player -- the damage itself may be a wash, but rolling to hit is fun, and it is something the game has very deliberately kept out of the hands of most clerics. So I'm really happy to see it back here.
Domain Spells (level 3). A reasonable list, esp. at levels 3 and 5, but the weird one is Leomund's Secret Chest. LSC has a material component cost of 5000gp, which makes it a weird spell to know automatically... except that one a cleric reaches level 10, they can cast it without material components. That's a weird interaction. It makes the LSC very useful, with no financial risk for the character.
Arcane Initiate (level 3). Two parts: Arcane Knowledge gives proficiency and Expertise in the Arcana skill. Compared to the wording elsewhere it's clear that if you start off proficient in Arcana you "lose" part of this benefit. This means you can have expertise in Arcana which is available to Wizards at level 2 (and Rogues at level 1). A Wizard who wants expertise in Arcana is going to be better than the Cleric, though, because there's no reason for the Arcana cleric to invest in Intelligence.
Cantrips give you the meat that changes the play experience of the Cleric -- you don't need to take the origin feat if you don't want to, and now it can also nab you True Strike -- you can now be an all-Wisdom heavy armor frontliner if you want.
Modify Magic (level 3). A defensive option and an offensive one. The offensive Tenacious Spell is powerful, but requires coordinated teamwork and at higher levels you still need to burn through legendary resistances.
Dispelling Recovery (level 6). Free Dispel Magic when you heal someone. How often is this needed?
Arcane Mastery (level 17). Free choice of four high-level spells is great, but it comes a bit late (and weirdly means that the cleric never learns any fifth-level Wizard spells).
What I saw as the main benefit of the class in 2014 is less needed now, but this is still a solid subclass and one I would want to play. Two changes I would like to see:
- Arcane Initiate. If you are already proficient in Arcana, then you gain a tool proficiency. That will help if you want to make magic items.
- Dispelling Recovery. Replace this with a single spell from the Wizard's list of a level that you can cast, that can be changed when you level up. It becomes a kind of magical secrets for you (like the Bard ability), and lets a cleric have access to fireball, phantom steed, and eventually one of the many awesome level 5 spells, or what you will.
