Consider the Ideal Climax; Adventure Climax

Source: Dungeon Master’s Guide p. 75

Adventure Climax

dice: d12Climax
1The adventurers confront the main villain and a group of minions in a bloody battle to the finish.
2The adventurers chase the villain while dodging obstacles designed to thwart them, leading to a final confrontation in or outside the villain’s refuge.
3The actions of the adventurers or the villain result in a cataclysmic event that the adventurers must escape.
4The adventurers race to the site where the villain is bringing a master plan to its conclusion, arriving just as that plan is about to be completed.
5The villain and two or three lieutenants perform separate rites in a large room. The adventurers must disrupt all the rites at the same time.
6An ally betrays the adventurers as they’re about to achieve their goal. (Use this climax carefully, and don’t overuse it.)
7A portal opens to another plane of existence. Creatures on the other side spill out, forcing the adventurers to close the portal and deal with the villain at the same time.
8Traps, hazards, or animated objects turn against the adventurers while the main villain attacks.
9The dungeon begins to collapse while the adventurers face the main villain, who attempts to escape in the chaos.
10A threat more powerful than the adventurers appears, destroys the main villain, and then turns its attention on the characters.
11The adventurers must choose whether to pursue the fleeing main villain or save an NPC they care about or a group of innocents.
12The adventurers must discover the main villain’s secret weakness before they can hope to defeat that villain.
^adventure-climax