The Vaanti Attack on The Celestial occurred in the final chapters of Act 3 in Endless Summer, Book 1. It was the culmination of hostility that occurred between a group of Vaanti (then known as "Watchers") and the occupants of The Celestial hotel - the Catalysts of Vaanti legend - on the Caribbean island of La Huerta. It was the first of only two battles between the Vaanti and the Catalysts before they called a truce once their unforeseen connection was realized; the Catalysts were in fact a vital part of Vaanti mythology and their collaboration was seen as necessary to prevent the eschatological event known as Raan'losti.
A confrontation between the Catalysts and unknown beings monitoring The Celestial was hinted as far back as Book 1, Chapter 7. In a predetermined exclusive scene in Book 1, Chapter 12, three of the Catalysts - Your Character, Jake McKenzie, and Sean Gayle - encountered Varyyn, a Vaanti prince, and a tribe under his command.
A brief fight ensued between the Catalysts and Varyyn's forces before the three Catalysts fled to the safety of The Celestial and warned the rest of the Catalysts of an impending attack by the Vaanti, who became known to the hotel's inhabitants as "The Watchers".
Although the odds of winning the battle were largely against them, the Catalysts prepared themselves and fortified the hotel, although a revelation nearly disrupted their plans.
Vaanti forces made their way into the hotel via various means, such as through hidden alcoves, windows, and even the rooftop. Varyyn in particular managed to make his way into the hotel by vine-swinging into Your Character's hotel room, forcing them and their best friend - Diego Soto - to flee and alert their allies of the development.
Fighting occurred throughout the hotel, notably in the lobby, where Lila Sethi set off a lethal water trap by letting loose wires electrocute the water which had flooded the lobby, and a group of Vaanti in turn. A corridor in one of the upper floors also served as a front in the battle with Raj Bhandarkar fighting off advancing Vaanti with the help of the artificial intelligence of IRIS.
The Catalysts met in a panic room in one of the upper floors of the hotel, where it became apparent that despite their valiant efforts, it was more than likely that the Vaanti would claim victory due to their superior physical abilities and greater numbers. The Catalysts soon made an agreement to charge out into the open for a last stand against the Vaanti. They were suddenly ambushed from above as they were initially led to believe the Vaanti had disappeared.
After surviving the ambush, the Catalysts made their way to the hotel's ballroom, where the fighting became desperate as the Vaanti unleashed non-lethal sedatives on the group, notably resulting in the temporary incapacitating of Michelle Nguyen. A portal gun was soon unleashed on the Vaanti, but during the chaos, Raj Bhandarkar and Grace Hall both went missing. While their locations were eventually revealed, it was apparent that there was only time to save one of them. Depending on the player's choice, Raj, Grace, or neither, was rescued.
With Vaanti forces arriving in overwhelming numbers, it became common knowledge among the Catalysts that they would not survive much longer and they had to make their escape. They grabbed parasailing gear from a janitor's closet in one of the higher floors and made their way to the roof, where they discovered there wasn't enough parasailing gear for everyone. As people volunteered to be left behind so others could escape, it was discovered the Vaanti were climbing the walls of The Celestial, effectively thwarting the parasailing escape plan.
As capture seemed imminent, it was hypothesised the portal gun could be used to transport them to another area of La Huerta, providing another escape plan. The gun was set into motion, but at the last second, Diego Soto was forcibly captured by the Vaanti as the portal encroached on the Catalysts.
The portal gun sent the remaining Catalysts six months forward in time. They each acknowledged who they lost amongst the fighting and, upon further inspection of the hotel, found it completely empty and ransacked. The Vaanti had abandoned the hotel after the Catalysts' escape. Realising they had to rescue their imprisoned friends, the Catalysts got some R&R before formulating a plan and leaving The Celestial for the Vaanti stronghold of Elyys'tel.