Sparkrender's Ritual

Sparkrender wants to claim the destructive magic that lingers on the Clifftop Observatory , just like his ancestor Eldenemir. Five days before the party arrived on the island, Aidron left the safety of Dragon's Rest and came to Clifftop Observatory. The two wyrmlings met and immediately clashed. Sparkrender attempted to turn Aidron against Runara, but the bronze wyrmling's hatred of chromatic dragons was greater than his disagreement with Runara. Ultimately, Sparkrender overpowered Aidron and imprisoned him in the observatory ruins (B6).
Sparkrender believes Aidron is the key to unlocking the Clifftop Observatory's magic and claiming his ancestor's power. With the bronze wyrmling imprisoned, Sparkrender began planning a ritual that will awaken the spirits of all the island's dead dragons and bing them to his will-at the cost of Aidron's life

The Ritual

If the party leaves the observatory without defeating Sparkrender, if they take a long rest before taking on sparkrender or if they fled and only returned after resting,they might return to find the blue wyrmling's ritual underway. The party arrives just as the ritual is getting underway. (If they destroyed the dragon effigies, they have been replaced by even cruder versions)

Streams of coloured light swirl through the air around the golden statue in the ruined rotunda. Each shimmering display seems to originate from one of the five dragon effigies you saw before, and the light's colours match the effigies' colour: Red, gold, brass, blue and bronze. A blue dragon is perched atop the sculpture, throwing his head back in pain or ecstasy as the light surround him and he unleashes a bolt of lightning up toward the sky.

To stop the ritual the party must face Sparkrender , potentially with the help of Aidron if they can free him of his chains. Any surviving kobold lurk here, but they stay out of combat if possible. Sparkrender will fight to the death- he has too much riding on the succes of this ritual to abandon it now.
Dragon spirits At the end of each round of combat, a random magical effect occurs, caused by the magical lights that swirl around the rotunda. These lights are manifestations of the dragon spirits Sparkrender is trying to bind to himself, but their effects are unpredictable. Roll a d10 and consult the table below

d10	Effect
1-2	Astalagan's Blessing Aidron + party regain 1d4+4 HP as the golden light surrounds them with warmth
3-4	Clyssavar's Flames DC12 Dex save for Sparkrender or take 2d6 fire damage as the golden light crashes into him
5-6	Eldenmir's Gift Sparkrender's Breath weapon recharges at the blue light enfolds him
7-8	Sharruth's Fury Each of the party must succeed on a DC12 Dex save or take 1d6 fire damage as the red light rerupts with fire
9-10	Turadaer's Tricks Aidron and the party gain advantage on attack rolls and saving throws until the next initiative 0, as the brass light shimmers arround them

Freeing Aidron Despite the three heavy chains that bind him, Aidron can still take actions such as biting or clawing at an enemy that comes in range, but he knows Sparkrender is immune to his lightning breath weapon so he doesn't bother using it. He might use his Repulsion breath if he can see a good use for it. A character can use an action to undue one of the three clasps that bind Aidron. Once all three clasps are off, Aidron is no longer restrained, though his speed is reduced by 10 feet due to the heavy chains. Removing the chains takes 10 min.
Disrupting the Ritual The most straightforward way to prevent Sparkrender from completing his ritual is killing him, but the party can also use their actions to interfere with the ritual and hinder sparkrender in magical ways. Some ways of interfering are:

• Manipulate the Effigies A character might use an action to lift an effigy closer to the central sculpture, breathe a prayer to the dragon it represents or otherwise coax magic from it. Doing so immediately triggers the corresponding effect
• Destroy the Effigies A character might break an effigy or throw it over the crumbling wall into the water below. This ensures the corresponding effect doesnt occur again (reroll)
• Manipulate the Sculpture Characters might try to manipulate the golden sculpture. The sculpture is large and sturdy, though, so a single action has no noticeable effect on the sculpture or the magic (the sculpture has AC 20, 27 HP). However, disturbing the sculpture does distract Sparkrender. The first time a character uses an action to attack/disturb the sculpture, the distracted dragon has disadvantage on attack rolls and saving throws until the end of his next turn. Once he sees the meddling isn't effective, he can't be distracted again