How can multiclassing improve my lvl 9 Paladin (Oath of Vengeance)

Question

Situation

I am a beginner D&D5e player (1y), playing an Oath of Vengeance paladin, thinking on multiclassing, playing with a fairly unoptimal and small group (w/ 2 wizard).
The world where we are is low on resources (or at least I feel like this):

• EU sized continent with max 50k population; there are weeks of wandering without any animal or humanoid/country, city, village anything), just plain vegetation
• Almost no wizards, clerics, druids, sorcerers (we found around 3 magic user within 9k person, ~10+ city/village)
• Not much money in the world and for the party (under 9 lvl we got total of 6k gold what was burned for wizards and health potions)
• Not much magic item exists (we got like 5 where a bag of holding, +2 spear and +1 magic wand the strongest)

This is a running campaign (not written in advice) and unsure how long we will survive or how long it will goes (what level PCs reach when the campaign ends).

My problem

Because I am the only melee and tank~ish* and healer in same time, I have hard time to put down some damage, move, heal. Most of the time I running back-and-forth to save NPCs or wizards, and am having a hard time usually to not die also.

I thinking on multiclassing my paladin at lvl 10 (currently lvl 9 and soon we will hit the next level). Why I think multiclassing helps:

• Get some cantrip (my DM will not let me take the feat where I can have 2 cantrip from clerics)
• Get some ranged option
• Get some extra lvl 1 spells

The options I see

• One level of warlock (not really tempting, hexblade is strong but in general I do not gain much since it is a paladin-first character, but eldritch blast is a very strong option and also a short-rest-reload for one 1st level slot)
• One level of sorcerer (more cantrip, more lvl 1 slot, shield, the firebolt is a good/okay ranged option)
• I would like to reach the lvl 5 slots, so I cant have too much multi-class

What are my doubts?

• Is it worth sacrificing the lvl20 vengeance paladin fly ability for a few slot? (I got advice as "if you don't have better option to fly on lvl 20 then you play in the wrong campaign")
• My DM is not supportive for multiclassing (despite personally he is a min-maxer munchkin power player); saying I had 9 level already to figure out how the paladin could be better/stronger
• What is the value of just a dip (only 1 level) into another class?

I seek experienced based answers ...

... from people who actually played paladin(s) and has more experience than me in D&D. The core problem to solve is a best build for a paladin & multiclassing in a suboptimal groups.

Char stats

Str: 18, Dex: 8, Con: 16, Int: 8, Wis: 10, Chr: 16.
I have the Polearm Master feat.
Race is a half-elf.

*tank~ish: I don't feel paladin as tank, has like ~2 point higher AC than wizards w/ shield magic, and usually (75%) I got hit by any kind of enemy because 20 AC is not that high.
By action economy, paladin has many concentration, save-or-suck spells and full action required mechanism.

Sidenotes

1. By lore both Warlock and Sorcerer is available, fit for the story (the campaign heavily influenced by Feys, but fey warlock is quite not impressive for me by toolset)
2. From official published sources we can use almost everything, but Tasha / Eberron / Any campaign material is banned or cherry picked apart.

Answer 1

You've written that you spend a lot of time running back and forth trying to heal people (probably provoking a lot of attacks of opportunity in the process!) You should consider multiclassing to bard, because you can then take the healing word spell and heal people from a distance with a bonus action. It's true that it's not a lot of healing, but if you're fighting something that deals 20hp damage on a hit, then healing someone to 1hp is equally good as healing them to 20hp.

The most common multiclass for paladin is to warlock, because you can then convert your warlock reusable spell slots into smites. I think this doesn't work as well for you since your warlock spell slots would be lower level. If you wanted to invest a lot of levels into it, it could be good. You might consider getting the celestial warlock for the ranged heal ability.

You've indicated you're considering multiclass to sorceror, but I don't think this is a good idea. You're currently the group's only melee character; if you switch to ranged attacks, then the group will have no melee character, which means your ranged characters will constantly be dealing with untanked monsters standing next to them. Ranged attack cantrips are not as good as your sword, especially since you're more invested in STR than CHA. Multiclassing to sorceror will not get you more level-one slots; it will just advance your existing spell slot progression (see here for multiclass rules), not add a new separate progression. Finally, note that most sorceror spells, including firebolt and shield, require somatic components, meaning you'd need a free hand (or the War Caster feat) to use them.

The most important thing you lose for multiclassing is not the level-20 capstone, because your game is probably not going to get to level 20. The thing you should worry about is the level-11 ability that adds +1d8 radiant damage to all your melee attacks. That's a large amount of damage! If you multiclass before getting that ability, you should recognize that you're putting off a large amount of combat power in your pursuit of utility effects.

My suggestion is to stick with paladin through level twelve (to get the +1d8 radiant damage at level eleven, and the +2 STR at level twelve), and after that multiclass into warlock or bard. If you're really suffering from the healing thing, you could multiclass one level now and then come back to paladin to get the above two abilities.

Answer 2

I would consider taking 1 level of Celestial Warlock. You get Sacred Flame and Light for free and 2 other Warlock cantrips of your choice.

You could take Expeditious Retreat which you can also cast on your steed from Find Steed.

"While mounted on your steed, you can make any spell you cast that Targets only you also target your steed."

You can use this to make an effective Hit and Run strategy (Mount moves in, you attack, mount disengages, mount dashes away). You'll also get another spell of your choice.

Finally, the Healing Light ability will essentially allow you to cast 2 free Healing Words per Long Rest without expending spell slots. Also, because the heals from Healing Light are not spells, you can use your Bonus Action to heal an ally within 60 foot range and still use your Main Action to cast a spell like Hold Person.

I had fun with this build (Oath of Ancients Paladin 9, Celestial Warlock 1) and I found it gave my character a little more versatility in combat as a fighter and a healer.

Answer 3

This entirely depends on what you want.

What do you want your character to be good at: tank, DPS, heal?

You are pretty out of luck for healing options as I think that the only way to boost your healing would be one level of life domain cleric but you don't have enough wisdom to multiclass to cleric.

If you want to be DPS, warlock is the right call. Between smite and hexblade abilities you should top the single-target-DPR charts. (Your spell casters have to handle area of effect damage and control.

If you want some ranged utility ability, warlock will give you that too.

As for tankiness: 20 is not bad AC as monsters should miss you more than half the time (most mounters have +7 to +9 at your level), but really you should have a +1 armor or shield or a ring of protection by now - your DM seems really stingy with the magic items. That being said you could multiclass into something with the defense style (fighter in your case) for an extra 1, but I don't think its worth it.

Not all tanking is about AC. As a paladin you get auras and the aura that increases your saves is one of the best defensive traits in the game. There is no shame in straight pally.