PortalAlarm

Portal Alarm displays a big raid warning on your screen whenever a mage in your vicinity opens a portal to anywhere that isn't Silvermoon City.

Features:

• Raid warning text across the middle of your screen
• Raid warning sound effect
• Random shame messages like "THE SUNWELL WEEPS. A PORTAL TO ORGRIMMAR HAS BEEN OPENED."
• Slash commands /pa and /palarm to test

Detected Portals: Stormwind, Ironforge, Exodar, Darnassus, Theramore, Boralus, Stormshield, Orgrimmar, Undercity, Thunder Bluff, Stonard, Dazar'alor, Warspear, Shattrath, Dalaran (Northrend and Broken Isles), Vale of Eternal Blossoms, Tol Barad, Valdrakken, Oribos, and Dornogal.

Silvermoon is the only portal that does not trigger a warning. As it should be.

Customization: Open PortalAlarm.lua and edit the WARNING_MESSAGES table. Use %s where you want the destination name inserted.

Compatibility: Built for WoW Midnight (12.0.1). The warning only shows on your screen — groupmates won't see it unless they also have the addon installed.

Source: https://github.com/Jtramey/PortalAlarm