See Raid under
Look for USERNOTICE of msg-id raid
Example message
@badge-info=;badges=turbo/1;color=#9ACD32;display-name=TestChannel;emotes=;id=3d830f12-795c-447d-af3c-ea05e40fbddb;login=testchannel;mod=0;msg-id=raid;msg-param-displayName=TestChannel;msg-param-login=testchannel;msg-param-viewerCount=15;room-id=56379257;subscriber=0;system-msg=15\sraiders\sfrom\sTestChannel\shave\sjoined\n!;tmi-sent-ts=1507246572675;tmi-sent-ts=1507246572675;turbo=1;user-id=123456;user-type= :tmi.twitch.tv USERNOTICE #othertestchannel
Checking what I have on file for outbound raids (as I misread your post initially, need more coffee)
UPDATE: You should be grab outbound raids from the moderation PubSub topic
See chat_moderator_actions