Hey guys, I'm creating a firbolg forge cleric and I while he hasn't seen any action yet, I am making long-term plans for how he would look by lvl 20. In particular, I am trying to find a feat that would be the most ideal for someone of this build. I just like the idea of him because, I mean, imagine an 8'2" beast of a humanoid charging at you with a mace and full plate armour and shield while shrugging off the fires engulfing him?? I'd straight crap myself

His starting stats, using point buy, are the following:

STR: 15/14
DEX: 8
CON: 14/15
INT: 12
WIS: 16
CHA: 10

The slashes are there to represent what the ability score could be depending on what feat(s) you guys recommend. By level 20, I am looking to have the following:

STR: 18/16 <-- 17/15 if I end up with the war caster feat
DEX: 8
CON: 16/18
INT: 12
WIS: 20
CHA: 10

Lastly, here are my proficiencies: Athletics, History, Persuasion, Survival

Here's my logic: forge clerics can become one of the most resilient characters in the game. I could try and play a tank/defensive role and maximize that to the limit, forgoing damage output in exchange for durability. In that case, maybe Tough, War Caster, or Heavy Armour Master would be ideal.

Alternatively, because forge clerics already get enough defensive perks as is, I can try to focus more on my combative side, and go for Weapon Master or Resilient CON (I might not choose war caster because I am focusing more an my martial abilities and would only need good CON saves to keep up elemental weapon or searing smite. Plus, I'd like that +1 to CON so I have some extra HP). Maybe also a dip into fighter for action surge? Or would I be better off keeping 20th lvl Divine Intervention since a forge cleric's melee attacks can do more damage than cantrips anyway?

Just as a fun idea: I could also take advantage of Powerful Build (assuming the DM interprets it to mean I can grapple huge enemies) and choose the grappler feat, grab enemies, and cast heat metal on myself once I am immune, or even just resistant to, fire damage :P. Just have my hugs melt them alive! 

Thanks for your assistance!

You want these guys to be big and scary? Firbolgs are the softest giants ever. However, you're putting some of their abilities to use. If you don't need to use them, take the Goliath race. Cause they are the hulking giants. Also, most campaigns don't go up to 20th level, but it is good that you're planning ahead.

Haha yeah I know but the backstory of my character has hardened his heart (think Kratos in GoW4; still kind of caring but inexpressive of it). Y'know, being tricked into burning down the forest and your people living in it would make someone pretty cynical, but he was always more results-oriented with a stay-out-of-my-way method of getting there. Plus, his motive for adventuring is that it might be his last chance to both see and save his daughter, so he's got that parental ferocity going on ;) 

The other thing is that with a goliath I do not get that delicious wisdom buff so, y'know, might as well make a firbolg with a distinct personality, right?

Probably want that 15 str for heavy armor. Definitely want war caster, not just for concentration help, but also for not having to mess with somatic component issues. And opportunity attack Cantrips can be fun. (They are great if you have an effect that gives you disadvantage on attacks, since then you can just force enemy to make saves.)
HAM is good at low levels, but it’s value tapers off as you hit higher levels; once enemies have magic weapons and elemental damage, it doesn’t come up so often. Taking it at level 8 is ok, level 12 or later is not so great. Though I guess it would get you to that even number in str.

The big question is how you’re going to get feats with the number of ASIs it seems you plan to take. If I’m reading it right, you’ve got four of those planned, so how will feats come into play? What am I missing?

I'm just interested in taking one feat and behaving like a melee cleric, if that help

Then I’d stick with war caster and those two wis bumps. Then focus on damage spells, since you’ll have a good, high save DC. At low levels it’s tough, but once you have more spell slots, it can work. That gets you through level 12. By then, you might have a better sense of what way you want to go, If you want another feat or more asi. 
Are you going to be the main healer? If so even more reason for the wis bumps to help with that. 

If you're only planning on one feat, definitely go with Resilient Con or War Caster.

Firbolgs are basically the BFG if he was a hippy, but the build seems legit.