So I am currently working on a home brew campaign about diving through the Hells to reach the Heavens, I need some help making the 10 plagues into mini bosses, so if anyone has some insight it would be greatly appreciated. 

I don’t know all the plagues off the top of my head, but I think fleas/lice is one?

Theres a lot of good swarms in the back part of the Monster manual that could work. Also there’s probably a lot of homebrew for some of that. 

I’ll look into some others, and see if I have any ideas.

Bulzeaus and Oinoloths are good pestilence bosses as well.

Thank you very much for the help! I’ll have to make sure to look at those swarms again.

I'd love to help, but would you mind reminding me what each of the ten plagues are? 

1-All water in Egypt ran red with blood

2-swarms of frogs invaded the homes of the Egyptians

3-swarms of gnats/lice plagued the Egyptians

4-flies brought disturbance/disease

5-all livestock fell sick and died bringing famine upon the land of Egypt 

6-boils incapable of being healed were placed on the Egyptians

7-hail and flames rained from the heavens 

8-hordes of locusts cape and destroyed the last remaining vegetation 

9-Darkness spread over the land of egypt

10-an angel of death stalked through the streets and murdered the firstborn of all Egyptian m families who followed the unholy Pharaoh

Edit: I already have a boss for plague 10 

okay that was actually so helpful, knew most of these but couldn't remember off the top of my head. 

1. for the first i'g either go with Stirges (because they suck blood) and fill them in the air, or do some form of ooze and make them look like or be blood.

2. I'd go with Slaadi and then make them very weak or Bullywugs.

3. For gnats and lice i'd pick will-o-wisps.

4. I'd pick some sort of fungi.

5. i'd just go with the classic zombie cows and stuff.

6. For some reason I thought of gibbering mouther, and i couldn't find anything else. 

7. elementals or ice and lava mephits (I love the mephits) 

8. for this i'd make my own stat for hordes of locusts or use a swarm of something in the back of the monster manual

9. I'd use a cloaker (massive) or an actual shadow.

Just be sure you either make sure all of these are made easier for the level your players are, or give them something that will help them win. 

This is incredibly helpful, and I thank you greatly for sharing your ideas with me. I will most definitely take all of these into account. 

What levels are your players and how many of them are there?

I have not yet started, but by the time they fight the plagues they will most definitely be around 14-15 level. I am not sure how many players I will have but probably around 3-4

Ok, and do you want a boss or an encounter like the earlier comments?

I’m thinking having the first through ninth be encounters with fairly easy mini bosses at their head, and The tenth will be just a boss.

Edit: I already have the tenth plague mapped out I mainly need help with 1-9

dude just so you know, this is such a good idea, I'm going to use it in my campaign!

Quote from spencerfletchernialo >>

dude just so you know, this is such a good idea, I'm going to use it in my campaign!

 That makes me incredibly happy and proud to hear that someone is that inspired by an idea of mine. I hope your players enjoy it! :)

A lot of these monsters can be easily found on *******/bestiary.html. There is also a feature here where you can easily change the CR of a monster, it's not perfectly balanced but good for a small shift.

1 - Maybe a buffed Dragonblood Ooze, along with a number of weaker versions of the same creature.

2 - A Froghemoth with Giant Frog minions

3 - Maybe an Ayperobo Swarm(A swarm of tiny demons but you can reflavor it how you want)

4 - Demon Lord Akyishigal could work well for this, it has elements of poison and has abilities that heavily relate to swarms of insects.

5 - I would go with a Devourer plus many undead creatures, probably Zombie Horses just described as cows or something.

6 - A Sibriex could work, it is CR 18 but you can put that down a little with the site above.

7 - A Balor could work, leveled down a little though. It has duel fire and lightning which is pretty similar to fire and hail.

8 - Arch-Devil Ia'Affrat is a posibility here, I'm really running out of high level swarm based monsters though.

9 - A Greater Shadow Horror or Hulking Shadow. Add in some Shadow Demons or shadows, respectively.

10 - An Ashen Rider would be good. This has elements of silence/stalking with its aura of silence and would be a good fit for traveling through the streets.

Hope these help. Again, the site above will be very helpful in finding any other choices. 

This site is also really good at creating/editing statblocks:

https://tetra-cube.com/dnd/dnd-statblock.html 

Wow! Thank you so much for taking your time to help me out with this! This is incredibly helpful and I can’t wait to check it out!

Something to consider with the Plague of Frogs: there's a grammatical irregularity in the original Hebrew text of Exodus 8:2 which refers to "the frog" (singular) as coming up and covering the land of Egypt. Every verse thereafter refers to "frogs" (plural), so there's an interpretation by some scholars that the plague was only one (potentially very large) frog at first, but as the Egyptians tried to kill the frog it multiplied into more and more. This is kind of a quirky take on the scripture but it has a long history, and it might be interesting for your encounter.

That’s really interesting. That also really helps to add some flavor to the encounter! Thank you for sharing that!

1- Vampire. or a nosferatu form VGR

2- froghemoth and grung

3- buffed swarm of scarabs that reanimates the skeletons

4- striges lead by strigori

5- loupe garou

6- onioloth

7- leveled down balor

8- an archimage with insect plague

9- buffed shadow

Interesting. That’s definitely very helpful, thank you for sharing!

Quote from GudranStonejaw >>

I’m thinking having the first through ninth be encounters with fairly easy mini bosses at their head, and The tenth will be just a boss.

 

Edit: I already have the tenth plague mapped out I mainly need help with 1-9

can I ask what you have planned for number 10, most dramatic of all?