- “A Cog Invasion has begun!!! (Cog's name) has taken over Toontown!!!”
- ―Toon HQ
A Cog Invasion is an event that causes a specific Cog to invade a district. They may occur randomly, but tend to be triggered with the use of a cog summon. Toons will gain double experience points for gags when they defeat a Cog during an invasion. The length of an invasion is supposedly random, with the exception of prolonged Mega-Invasions.
- Main article: Cog Summons
A cog summon is a reward which grants a Toon the ability to either summon a specific Cog, cog building or cog invasion. They are granted by Bumpy Bumblebehr if the Chief Justice is successfully defeated. The rewarded summon is random, however, cannot be a summon that is already being carried. A cog summon can be used by opening the "Cog Gallery" page in the Shticker Book, and clicking on a small button next to a Cog's face and selecting a summoning option.
Toontown Rewritten has its own invasions API, which provides an updated list of invasions by districts. The API, available in the JSON format, provides information about the invading Cog type (and also mentions if it is a Skelecog or a Version 2.0 Cog invasion), the size of the invasion, its progress, and the time at which the API, as well as the invasion data for each district, was last updated. The API allows retreiving the invasion data from other websites as well. If an error occurs, the API only returns the error.
- There was a Version 2.0 Cog invasion that occurred in May 26, 2014. Doctor Surlee, who was part of the "Valley group", sent a memo to Toon Headquarters to let them warn all Toon that v2.0 Cogs were taking over Toontown.
- Starting in July 4, 2014 and ending a few days after, Legal Eagles invaded Toontown, along with v2.0 Legal Eagles and Skelecog Legal Eagles.
- The first cog invasion were Movers & Shakers.
- There have been several occurences of Skelecog and v2.0 Cog invasions.
- Starting on August 16, 2014 and ending a few days after, Telemarketers invaded Toontown as v2.0 Cogs and Skelecogs.
- Throughout the weekend of October 10, 2014, Toons gained triple instead of double gag experience points during invasions as part of Double Experience Weekend.
- As of 2015, you can get double experience in a Cog headquarters regardless of an invasion.
- There was a Version 2.0 Movers & Shakers Cog invasion that started on July 31st, 2015 and ended on Aug 1st 2015. This was known as Phase 1 of 2015's Storm Sellbot.
- If you stay in groups while fighting, even the weakest of toons have a chance against high level cogs. After all, they sure say that strength is in numbers.