D&D 5E Help me build an epic final battle with Tiamat!

[THEMNGMNT]

I want to express my thanks to everyone here who replied to my original post. Your thoughtful replies helped me shape a satisfying climax to my 122 session campaign. In the end, Tiamat was defeated and good triumphed...for a while, at least.

 

[Disgruntled Hobbit]

Do a multiphase fight

Start with Tiamat coming out of a portal while people are summoning her from the outside
Have the PCs deal with the summoners at the same time as Tiamat. With pillars charged with elemental energy tied to Tiamas's heads (that can absorb breath weapons but occasionally pulse with energy)
Then when they disrupt the summoning everything in the area gets sucked into Hell

Give the heroes a few rounds to heal and then a healed Tiamat emerges
The terrain is cracking from the failed portal with growing pools of lava and earthquakes

 

[Sword of Spirit]

Mordenkainen's Tome of Foes includes abishai servants of Tiamat of all 5 chromatic colors. A battle with her should include plenty of those in addition to chomatuc dragons.

 

[Quartz]

In the end, Tiamat was defeated and good triumphed...for a while, at least.

Tell us more!

 

[Wyldekarde]

Tell us more!

I agree! I'm curious how you went about setting it up for the players?

 

[Queer Venger]

I'm nearing the end of my first 1-20 5E campaign. The player characters are about 10 sessions away from facing off with Tiamat in the (hopefully) epic finale.

The PCs are 20th level with multiple epic boons and a robust set of magic items. When it comes to tactics, they are middle of the road--neither great nor terrible. (Same with me, to be honest.) We play on Zoom using theater of the mind supplemented with maps (but no tokens).

Elf arcane trickster rogue
Aasimar vengeance paladin
Half-elf whispers bard
Halfling lore bard
Tiefling shadow sorcerer
Human beast master ranger

Tiamat is plotting her escape from Hell. So the PCs might confront her in Hell...or they could let her escape and then ambush her on another plane. TBD.

I don't want this fight to devolve into a dice-rolling slog--I want it to feel like the climax to an epic fantasy blockbuster.

Does anyone have advice on how to play Tiamat for maximum effectiveness, excitement, and drama?

And how about pointers on terrain, minions, or anything that can make this finale feel like it has majesty and grandeur?

Thank you!

You went to 20!! I applaud you! I ran a Planescape campaign and my group got to 17 and I honestly could not challenge them. I hope it ends epic but with Tiamat I would not hold back and hope they TPK gloriously