Siege Magic

The school of Siege Magic is a splinter school of Evocation magic, sacrificing precision and careful control over the elements for sheer destructive power. Wizards of the school are often tasked as demolitionists, sent to clear harsh terrains and ruins in order to make way for progress. Others, however, use Siege Magic to wreak havoc upon the world, as seen in the hands of anarchists and other ruinous factions. 

Destructive Arcana

By 2nd level, your constant experimentation with forceful magic allows you to dismantle the arcane and reshape it into destructive forms. When you cast a spell of 1st-level or higher that deals damage, you can change its damage type to either fire or thunder damage.

Siege Tactics

At 2nd level, you learn to strike swiftly, breaking through enemy defenses before your allies rush into the fray. You can give yourself a bonus to your initiative rolls equal to your Intelligence modifier.

Explosive Arts

By 6th level, you learn how to bring out the volatile properties of destructive spells, igniting your enemies and shattering through stonework.

When you cast a spell that deals fire damage, it ignores resistance to fire damage, and each creature affected by the spell takes additional fire damage equal to half your wizard level at the start of its next turn.

Moreover, when you cast a spell that deals thunder damage, it has the Siege property (your spells double damage to objects and structures).

Demolitionist

At 10th level, you cause the earth to tremble as your magic breaks the ground beneath you. When you cast a spell of 1st-level or higher that deals damage in an area of effect, you can cause the ground in that area to become difficult terrain for 1 hour or until cleared, with each 5-ft-diameter portion requiring at least 1 minute to clear by hand. Alternatively, if the area of the spell overlaps with an area of difficult terrain caused by obstacles on the ground such as loose earth, stone, plant life, debris, and the like, you can instantaneously clear that area of difficult terrain.

Mass Devastation

By 14th level, you are a master of destruction, capable of wreaking havoc on a larger scale. When you cast an instantaneous spell of 1st-level or higher that deals damage in a single area of effect, you can expend an additional spell slot of 1st through 5th level. When you do so, you can add a number to the total damage rolled equal to 5 times the level of the spell slot expended. Moreover, you can also cause the size of the spell's area to increase by up to 5 feet times the level of the slot expended when you use this feature.

Once you use this ability, you cannot do so again until you finish a long rest.