Glyph of Fortification:

Glyph of Fortification is a team-wide defensive ability that temporarily protects buildings and units from damage and can be activated from anywhere on the map. In Dota 2, it is used to stop enemy pushes, buy time during defenses, and protect a base during key fights or objectives.

Because it affects the whole team, Glyph of Fortification is an important part of map control and base defense, especially when high ground structures are under threat.