I just asked my self what are the effects of a Titan impacting on to a planet.

Well if the Titan crashs on the planet as some dust battles indicate, Caldari prime will face a extinction level event.
A leviathan class Titan is around the same size as the meteor that hit earth 65 mio. years ago that formed the chixculub crater in Mexico and removing the dinosaurs. The crater has a size of 160 km reaching 10 km in to the ground.
Of corse this meteor was not made of super robust alloys, covered in armor plates, had no shields an was not filled with, reactors, warpcores, jumpdrives, jump fuel and plenty of amo to destroy half a solar system.

The shockwave of a meteor impact will travel around the planet with supersonic speed leveling al the buildings in its path, creating serval earthquakes of high magnitude, eruptions of vulcanos and super tsunamis on the oceans. The heat of the shockwave would ignite serval large scale fires around the globe, burning most of the plants and city's.
the melted material of the impact would be thrown in to low orbit leading to serval high energy infrared radiation burst up on reentering the atmosphere, killing plankton insects bacteria and creating acid rain across the globe. It would change the composition of the atmosphere by reducing the oxygen level and adding carbon dioxide and other gases.
For the next 10 years or more, the atmosphere is so saturated with particles that only 10-20% of the sunlight will reach the ground. Leading to an ice age/ nuclear wither, or in case of Caldari prime reverting the planet to pre terraforming conditions.

In case of a Titan instead of a meteor, you can ad a mix of toxic and radioactive materials being spread al over the surface. With in an hour most of the population and animals would be dead, some will survive if they are lucky and in fortified underground facilities or in submarines diving.
Lets hope that if the titan goes down, it has a very brave captain with honor and love for nature (yea i know Caldari and honor, two things not going along very well) and some propulsion left to preform a crash landing instead of full impact. So it destroys only some citys instead of the whole surface.