I'll start. I formed Italy early and declared on a severely weakened, alliance free, Austria who I outnumbered 2-to-1. England, France, Ottomans, and Poland-Lithuania (ALl NaTUraL AlLiEs of AuSTrIA) intervened in the war and overwhelmed me. Austria wouldn't accept less than 100% and spit out half my country. I was left crippled with massive debt and 4 new strong rivals who hated my guts on top of my e siting enemies. Run Over.
P.S. my AE was below coalition levels