A D&D 5E Character Building Quandary

I'll start off by saying I'm not entirely sure this is the right place to put this, or if there's even a "right place" here, but anyway:

A month or two ago I found a local gaming store that has D&D Adventurer's League nights every Wed/Sun and ever since then, I've been going every week and having a lot of fun. I started off playing a human monk, but once tomb of annihilation and the Adventurer's League materials that surrounded it released, I created a new character to play on "meat grinder mode" (all death saves are increased to dc15, but 10% extra gold and xp) just for fun.

After the first couple sessions, I started to develop a backstory for the goliath fighter I created that night. Loosely, he was abandoned by his tribe for some unknown reason, and subsequently taken under the wing of a paladin of Helm, god of protection. He was trained by said paladin in the ways of combat and religion, though the goliath heavily struggled with the latter aspect. Despite this, he joined the order of the gauntlet (a faction of mainly paladins and holy warriors of good, for those that don't know) and set off on a mission to chult (the setting of the campaign) upon the request of said order.

So, with all that out of the way, the quandary mentioned in the title of this post is I'm not entirely sure how to go about building him. As mentioned previously, he's currently a fighter, but I would like him to eventually overcome his divine troubles and potentially multiclass into cleric or maybe paladin. (I'm iffy on paladin because of the tenants, but it might work as a way for him to overcome those divine troubles) However, since I chose to put him into meat grinder mode, I feel the need to be somewhat munchkin-y in order to survive. (and there's also the fact that my current party is somewhat struggling without some kind of healer) Essentially, I need some advice on how to build a "holy warrior" that can put out some healing while still being a tanky guy with a greatsword. (also note that since he's below 5th level currently and I'm playing in adventure league, I can just re-spec everything while keeping my gained xp.)

What are your character's attributes?

He's got STR 16, DEX 12, CON 16, INT 8, WIS 13, and CHA 10. Like I mentioned though, since he's yet to hit 5th level I can re-spec all of that as long as I stay within point buy/standard array.

I have to say I like multiclassing Cleric, especially for Tomb of Annihilation. Here are my somewhat disorganized thoughts as to why:

1. Cleric gets much more diverse spellcasting options, including a lot of survival-oriented spells. Being able to reconfigure your available spells every day gives you a ton of versatility. You might not take Create/Destroy Water as a Paladin

2. Fighter compliments a full spellcasting class well. Proficiency in con saves means you can keep those buffs up longer compared to regular clerics, and action surge means casting two 1-action-casting-time spells in one turn, which even a 20th level cleric cannot do.

3. Clerics get cantrips, which don't expend resources. Guidance can just buff all of your party's skill checks, including survival rolls for hunting/gathering, navigating, etc.

4. Cleric has less overlap with Fighter than Paladin, and some features on Paladin are redundant when combined with Fighter. The Fighter's 2nd attack doesn't stack with the Paladin's, and getting a second fighting style is not bad but not great. If you do end up going Paladin, then try to multiclass as soon as possible so that you don't delay the 2nd attack, or just dip for a couple of levels after you get 5 levels of fighter.

5. Paladins don't have an option to heal as a bonus action, so if you are healing in combat a paladin has to spend their action. Clerics have healing word as a bonus action heal, which will allow you help your party at range and avoid the meat grinder death saves without ever missing your action.

6. A Cleric's Chanel Divinity is going to help out with those jungle zombies and the other numerous undead in the game.

7. A Cleric will gain slightly fewer HP than a paladin and smaller hit dice, but not by much.

8. Paladins have smite, which is awesome. It grows rather slowly. Just for the record, spell slots from a different class can be used to power your smites. Paladin/Bard, Paladin/Sorcerer, and Paladin/Warlock are all common multiclass combinations for this reason. Since you said you wanted to make a tank rather than a DPS character, smite is probably not that important to you.

9. As far as cleric domains go, I think Nature would work great for Tomb of Annihilation

10. Definitely recommend the War Caster feat for a Fighter / Cleric! Depends on how strict your DM is on the particulars of casting spells, but if they run the game tight to the rules as written, it will be essential. Pick it up at 4th or 6th level when your fighter gets the ASI / Feat.

Regarding #2, just be careful you don't try to throw in a spell that uses a bonus action like Healing Word. If you do that, there's a specific rule that will prevent you from casting any other spell during your action surge except for cantrips that take one action (PHB pg 202).

Thanks for all the help! (and the clarification on that one rule)
I do have a few more questions though: Why nature cleric? I've went and read over the features for that domain, and nothing seems to be very enticing over, say, life. (which is what I had been contemplating previously.) I've looked over their kit up until 4th level (which is around how far I currently intend to delve into cleric) and I can't seem much besides their channel divinity that interests me, and even that is fairly situational.
My other, and last question, relates to my plans to only go to 4th level: Does that seem a good place to stop? Or are there better things that I'm not noticing that are worth going further in cleric rather than taking fighter higher?

Hey my pleasure! I wish there was more talk like this on the forums. And thanks CancerMan for the reminder on the bonus action spell rule.

Life Domain is great. I also like Nature Domain because:

1. You're in nature for a lot of this campaign. I haven't read it, but I bet you're going to face a lot of deadly plants and animals (like Dinosaurs). The nature cleric's special channel divinity to charm all animals and plants in an area of effect (with saving throw to resist) can really swing an encounter in your favour. You don't need to heal if you slaughter charmed enemies or avoid the encounter all together.

2. The domain spells seem pretty useful for an exploration heavy campaign. Also, unlike Life Domain, it gives you access to spells that clerics can't normally take. Animal Friendship and Speak with Animals can be used for some creative problem solving and intel gathering. The value of these spells often depends on the DM and the adventure, but I suspect that it will shine in ToA.

At 3rd level you get Barkskin which is pretty useless because you will usually have armour on (unless they're using the new sleeping in armor rules), but spike growth can be a great control spell, slowing down or completely blocking mobs of weaker creatures.

3. Getting a druid cantrip is nice. Cantrips in general are fantastic in a survival game because they use no resources. Druidcraft is great for predicting the weather to improve your chances of navigating successfully in the wild, and maybe some of the other modes will come in handy. Mending is great. Repair your ranger's broken arrows so they don't run out of ammo, or patch those holes in the canoe that went over the waterfall, for example. You probably already took guidance as a Cleric cantrip. For damage, poison spray might be pretty sweet because you're in melee anyway, and remember that the damage scales at CHARACTER level, not cleric level. It sucks that it takes zero damage on a successful save though.

4. The additional skill you get (Animal Handling, Survival, or Nature) is going to be helpful in this ToA.

5. Heavy Amor proficiency is wasted, sadly.

Final disclaimer - I have not played or read Tomb of Annihilation, so my advice might be totally wrong in regards to things that I suspect will be good.

Will post later about levels, but at a glance, 4 levels of cleric seems good.

So, I'm going to assume your character is going to max out at level 11, because that's what the adventure says characters max out at.

So, if you go Cleric-4, then you get to Fighter-7. The 7th level of fighter gives you a Martial Archetype feature, which is either Remarkable Athlete (Champion), Know Your Enemy (Battle Master), or War Magic plus 2nd level spell slots and a new spell (Eldritch Knight). I get the feeling that you're not going the Eldritch Knight path, so I assume you're looking at Remarkable Athlete and Know Your Enemy for level 7. They aren't bad but not great. I suppose every level you put into Fighter also gives you +1 on Second Wind, but that's pretty minor.

If you go Cleric-5, Fighter-6, the 5th level of Cleric gives you 3rd level Cleric spells, Destroy Undead (CR 1/2), and 2 new Domain Spells. There are some powerful Cleric Spells at this tier, and depending on your domain some sweet additional spells.

When gaining levels, I'd recommend getting 1 level of Cleric as soon as possible, but only one. That way you have the added survivability and utility of Cleric in the early levels when surviving is hardest. But, don't take any more cleric levels until you get Fighter-5, where you get extra attack. Then you can get cleric or fighter levels in any order, depending on your needs.

Hope these musings are helpful!

I agree with Len's assessment of the situation. Fighter 6/Cleric 5 is the way to go

Fighter 7 doesn't get you much, while Cleric 5 gets you third level spells, which can be totally amazing.

Alright, you've won me over to taking cleric deeper. The main reason I had aimed at cleric 4 was the fact that Revivify was one of the life cleric's spells for that level, and due to plot reasons, that spell is useless. A look back over the regular cleric led to seeing Mass Healing Word and deciding that that's something that'd probably be good to have.

However, since this is adventurer's league I don't have to stop at level 11. Any character can be in essentially any adventure, so I'm planning on taking this character (that I've been really enjoying playing) to whatever the next adventure is when it comes around. So since you touched on fighter archetype, I'll go ahead and mention that champion is what I'll be going with. Now back to the multiclassing specifics: which is better? fighter 15, cleric 5; or fighter 12, cleric 8. I have a feeling that the latter is the best option, as it keeps more ability score improvements and gives higher spell slots, but the former keeps the champion ability of criticals on 18. (which is probably almost definitely not as useful as it seems) I'm basically decided at this point, but there might be something I've missed.

Also, since I plan to keep this character after he leaves the tomb of annihilation setting, I think I'll be going life instead of nature (though I do definitely see the benefits of going the latter instead, there's another player that's heavily considering multiclassing nature cleric. And I know there can be two of the same, but considering I was still conscious while over half my party of 7 was down last session, I have a feeling I'll get a lot of use out of life cleric's channel divinity.)

And thanks again to everyone for sharing your massive banks of rpg knowledge with me!

So I've thought it over, and decided I would build Fighter-12, Cleric-8 would be the way to go. I think War Domain Cleric instead of Nature and Battle Master Fighter would be the best archetypes to pick with the 12/8 split, but make whatever feels fun to you :)