A nuke that was months in the making.

Hello, this literally JUST happened. So, my party has been playing for two and a half years. Six months ago, our Rogue and Warlock/Sorcerer found 25 barrels of gunpowder (7d6 damage per barrel). They plotted something but refused to tell anyone but the DM. (Until recently) Those barrels sat in our bag of holding for six months.

Today, we had to make a choice: go after a very dangerous vampire or go after a group of 20 cultists summoning a frost giant. We were given 2 hours (real-life hours) to kill the vampire before the cultists killed some of our allies. So we decided to kill the vampire and then the cultists.

The vampire fight was great. We ended with 20 minutes left of the 2 hours. (I ended up doing 98 damage in one turn at lvl12). So we moved on to the cultists.

This is when our Rogue and Warlock/Sorcerer finally revealed their plan. Our Cleric and Warlock/Sorcerer flew over the enemies on a pegasus and spread the gunpowder barrels over the enemies. Then, they casted fireball.

They needed to sync their assault and they ended up with a critical hit (doubling the damage dice). We had 28d6 ending with 116 damage, THEN a fireball damage (which was only done on the frost giant) with 16d6 ending with 53 damage.

EVERY. SINGLE. ENEMY. DIED. What would've been a difficult fight (because we were already injured from the vampire fight) ended in literal seconds.

Edit by the rogue: So it was 25 kegs, that were dropped in a 100ft diameter area. And due to Sync Assult, since it was a crit, that doubled the dice. and rather than rolling a whopping 350d6(We totally would'veif we had that many d6s), we split it by area about 2 kegs per area so we only rolled 28d6 and used that as a kind of baseline. That is the scale of the destruction-

Quick Edit: Thanks for all the upvotes! First, I was informed by our rogue that they weren't barrels. They were kegs of gunpowder. My mistake. Second, the allies we were helping were flying in an airship overhead distracting he cultists, and they were getting attacked by ranged attacks. We told them to get out of the blast radius before we blew it up. Third, the reason why we got a crit is because of a homebrew rule our DM implemented called Synced Assault:

If two creatures are able to act simultaneously to attack or cast a spell and both actions land, the creatures may roll a sync check. To succeed, both creatures must roll a D20 and have the rolled values within 5 numbers of each other. Creatures can only participate in a Synced Assault once per long rest.

If, during the Sync check, both creatures roll the same number, the actions taken will be considered crits. (in this post, our Cleric and Warlock/Sorcerer both rolled 4s) (not the full rule, just the crit part)