Demolition

XCOM 2 is all about taking cover and flanking enemies in order to get the kill. There are several of ways to demolish the cover and they are listed below:

1.) Grenades

2.) Grenadier's "Demolish" skill.

3.) Psi Operative's "Null Lance"

4.) Ranger's melee attacks have a chance to destroy nearby cover surrounding his / her target

5.) Large enemies rampaging through walls. Sectopods and Gatekeepers do not go around obstacles, they just plow through their way to get to their desired spot. By hacking / mind-controlling them, respectively, will allow the player to destroy much of the cover.

6.) Missed shots hitting the cover instead will have the chance of destroying it (but the chance of totally removing full cover is slim to none.)

7.) Archon's Blazing Pinions will destroy the floor it will hit.

Demolishing cover and the floor where the enemy units stand will allow the player to gain advantages like,

Higher hit chances

Instant-kills for immobile Turrets

Extra damage from fall damage

New lines of sight, specially for Sharpshooters on top of the roof, or the nearby building's roof.

Disallow non-flying enemies to reach units traversing the roof. This is extremely useful for units carrying VIPs / traversing VIPs and during a chaotic evac.