MEME REFERENCE

Smash Bros.

Use to announce that a new participant, faction, idea, or complication has dramatically entered an ongoing conflict.

What it expresses: An existing contest changes when another combatant joins the field.
Example: Two departments debate a policy until legal adds a third position, and the chat announces that legal joins the battle.
When not to use it: One side quietly leaves and nobody new enters; the battlefield has shrunk rather than gained a participant.