Particle Editor
In Source2 particle effects are very powerful and can render almost anything in the engine such as sprites, lights, models, text, as well as run physical simulations.
The Particle Editor is a powerful tool that allows the creation of these particle effects, you can create effects from simple ambient particles such as leaves dropping in the wind or dust motes in the air to complex physical simulations involving thousands of particles.
Info
Parts of this section were taken from Nibuja05's dota particle editor tutorial with the author's permission.
The particle editor is disabled in 
Counter-Strike 2 by default, to enable it go to
steamapps/common/Counter-Strike Global Offensive/game/bin/sdkenginetools.txt, in m_EngineTools find the m_Name = "pet" section
and comment out csgo from m_ExcludeFromMods.
