My Homemade Effect Charts Unintentionlly Cause The Death Of The Cleric and an Important NPC

For background, I am currently running a 5e campaign that I have homebrewed at certain points to make things in the game more fun and random over all. My players are as follows: Daeth "Brambles" Bunder, a veteran Halfing fighter who fought in various wars throughout his time and had become a grizzled man with a burning hatred against Kobolds, Pelaios, a Tiefling Monk who was sent off by his master at the monastery to go and observe the world and learn from it first hand, Baba Ganouche, a Goblin Wizard specializing in Divination magic that he learned from his 'family' of Gypsies (Vestaari I believe they're canonically called?) and stacked with a high charisma score to try and fool his way through his half-assed divinations that he peddled in his earlier levels, and finally the member in which this post is labeled after, Kepesk, a Kord-worshipping lightning domain Cleric whose cold-blooded reptilian mind struggles to adjust to the ways of the civilized world after he left his tribe near Baldur's Gate so that he would be able to find truely capable individuals to help him grow stronger in his quest for martial improvement.

Together, these four met in the stereotypical tavern and exchanged names, eventually leading to them going to clear out some goblins that were attacking nearby trade caravans coming from their starting town of Stonewallow, an above ground Dwarven mining town run by a geritocracy of three elders and one High Elder. Taking the tasks from the rangers hired to scout the nearby trails in the employee of Stonewallow, the party goes, fights off the Goblins, and recovers a strange shard of an ore-like mineral they had never seen before.

Being the overly-ambitious type that I am, in the weeks up to the campaign, I devised a whole system revolving around these shards, which were secretly pieces of an avatar-like being that existed way before Toril was properly created. This being was known as the Avatar of Change, and I devised this being to be the Avatar for not a deity, but a singular massive being with the power to do such a thing. What could possibly have the power to generate an avatar without being divine itself?

The answer, a living, sentient planet. Namely, Alabar the Changer of Ways. Anyone who read through 4E MM3 may have seen this Alabar, and I always wanted to make some use of him in a campaign of my creation.

These shards that made up Alabar's avatar had special properties to them that whenever the life force of an entity, living or dead, comes in contact with any amount of this material, it magically effects the being whose life force touched this shard. For clarification, life force to me consists of blood, ichor, etc.

I hand wrote an entire table of effects that the players would have to roll on if any of their blood ever got onto this shard, though I didn't make it all bad. Change isn't always intrinsically evil after all! Some effects involved vomiting forth a belly full of writhing maggots, being blessed with ancient knowledge that temporarily boosts your Wis/Int modifiers, and many other eldritch horror like effects.

One other attribute about these shards is that they have a VERY strong pull on each other, and when more than one piece gets within five feet of each other, if nothing is obstructing them, they will fly towards each other and morph into a larger chunk of the avatar, which on its own has an even stronger pull on shards than before.

Of course the question now begs... what happens when enough come together?

Fast forward to that fateful day.

The party returns to Stonewallow after hunting a Bulette that had recently assaulted the nearby apiary (bee/honey farm) to find it under siege by a very large Goblinoid war host. Goblins, Hobgoblins, Bugbears, Ogres, and many other fierce beasts of war stormed and assault the town, many of the guards being slaughtered and various buildings being sacked for their valuables. Ballistas fired upon the Elder Hall, which ultimately survived after the party defeated Draughn, Hobgoblin Siegemaster, and busting up all his toys he had in reserve.

Running to the Elder Hall and ensuring the elders were safe, they noticed one was missing. Hilga Bronzeblood, the only female elder and also town blacksmith, was captured and taken back to the War Camp that was home to the invading Goblinoids. After securing the Elder Hall by clearing out the two attacking Ogres, the party meets the leader of the initial assault force, Grix the Beast Master. After unleashing his pet Triceratops and nearly downing the Wizard, Grix ultimately succumbed to his wounds, and shattered the morale of the attacking goblinoids. Taking time to recuperate, the party follows the trail left by the remaining horde and reach their destination... the war camp.

Drums beat loudly, cries of martial victory and savage feasting sounded out as the party marches up to the main gate, guarded by two Ogres holding up the gate and acting as the mechanical component to the pseudo drawbridge. After a successfully passed Deception check by Baba Ganouche saying he was bringing in three prisoners, the Ogres dumbly agree that 'Dis must be da big bosses order he said before!' Making their way in though, the deception is torn down almost instantly.

Standing proudly within the center of what could be considered a cleared around training yard/combat arena, a burly Hobgoblin with grayed hair and near pitch black armor, War Master Varn, called out in admiration to the party for choosing to walk so boldly into his home. Hearing the words of their master, the other Goblinoids and Ogres manning the battlements all started chanting and hyping up their War Master, with two Bugbears holding the captive Hilga Bronzeblood to the side so she could see what would soon occur. Tension rose, and deadly combat would soon ensue. Giving his final words to the party, he whistles and holds up his arm high into the sky, heavy wing beats soon following as he is picked up by a horrifying Wyvern, trained to be his personal mount for combat.

As Varn drew his blade for combat, the party soon saw that his sword was made up of ENTIRELY melted down Shards of Change. This, of course, made the party members realize that it was time to take the gloves off, and that they were going to need to be careful in more ways than one. Up to that point, after witnessing the fusion of two shards earlier in the campaign, the party made sure to keep this larger one under complete lock and key, specifically putting the malicious chunk into their (very luckily rolled for) Bag of Holding. Realizing the implications of this fairly quickly, I admired their forward thinking out loud and rolled for initiative.

The battle was bloody, and big damage was dealt, but almost all the party members have over half HP with the Wizard down to slightly below half. All was going well. The War Master, swooping down atop his Wyvern mount, went to strike at Kepesk the Cleric, and he activated his Thunderous Rebuke ability, that made Varn take enough damage to fall dead from his Wyvern in a twitching heap.

Because Kepesk was struck by this Sword of Change though, he had to roll a D20 to determine what the effect was that he got. After checking my notes to see what effect he got... I paused. I'm not a malicious DM and, in a way, hate seeing my players lose their characters for dumb reasons. And yet, the events that occurred afterwards have effectively shaped my campaign to this day.

The effect Kepesk rolled on was as follows: 'Imperceptible to the naked eye, you feel an ethereal tendril coil around your body and sap it of magical energies on your person, draining all items of their magical effects and nullifying any magic you have active right now.'

Slowly, the party realized the catastrophe that was about to occur. Kepesk was the one wearing the bag of holding, and this effect made the Bag of Holding just a regular bag. Now, if it weren't for the dragon's horde of gold that they had accumulated weighing it down, this may have gone differently. Instead, over 20,000 GP worth of coins erupted from the now destroyed bag of holding... and the chunk of change too erupted forth, instantly pulling to the large sword crafted of the stuff... and morphed into the most dangerous Aspect of Change that I had created.

In the place of where the sword and shards all collected and shifted, stood a Star Spawn Larva Mage, a CR 16 monster against a party of level 6's.

At that point, I could have just cast Circle of Death and TPK'd my players, but I couldn't bring myself to bear. I skipped certain actions available to it, justifying that it had just spawned from non-existence and needed time to collect itself fully. Making use of it's binding abilities, it trapped Kepesk, Hilga and Daeth for a time, Pelaios and Baba Ganouche already formulating how they would escape. Goblinoids all panicked left and right, scrambling to retreat to the forest once more as their once proud leader lie dead and replaced by something they had never seen before in their lives. The moment was complete chaos.

In that moment, the Cleric made his decision. He turned to his friends and said 'Go, let me slow down this monster before you all die!' Breaking free from the binding worms, Daeth grit his teeth in frustration, and sprinted away with Pelaios and Baba Ganouche, looking behind to witness the haunting sight of this larva mage consuming the flesh from both Kepesk and Hilga, who was not able to break free herself.

Kepesk fell in order to protect his party, standing against an enemy that I was not intending to have come out that early in the campaign. The Elders mourned the loss of their sister, and in a way, this victory was very bittersweet. Evil won in a way I could never have predicted, and the party felt loss for the first time.