Speaking of lolmassive incursions... During the Glorious Holy War for Friuli, as the Fraticelli religion held by Italians became dominant finally allowing me to HW them, the Basileos decided it's a good time to declare a war over some bullshit city or a single reason, I don't even know what.
Suddenly I was up against 50k troops with about half of that available from levies, vassals and retinues with a war still going, though ending, in Italy.
Since I'm controlling The Statehood Formerly Known As Venice, plus I hold a good chunk of Germany, all of Bohemia and western Poland up to Lithuania, I had about 3k in spare gold, so I was able to supplement that with Mercs, and since Basileos ran out of dosh literally seconds after declaring on me, 3k of his mercs flipped.
Some doomstacks crashing into each other later, I got the warscore to +50ish, and since paying the mercs and retinue regen cost more than I would get by forcing ol' Basil to surrender, I offered him White Peace.
Aaaaaand it bit me in the ass a couple years later as, of course, that douche declares the exact same war again. Once again I beat him back, albeit with some losses, but as I get tardy with my Merc shots I catch a bad case of lolgettingcaptured after getting +50 warscore again and losing immediately.
The moral of the story being short and known to some: 'Kick the son of a bitch while he's down.'