When Italy joined the war against the Central Powers, the Austro Hungarians actually came out slightly stronger. While they were having difficulties maintaining a front against Russia and against Serbia, the Italian ambition at taking Southern Slavic lands created a purpose for the war for the Slavic AH populations. Czechs, Croats and other slavic groups could finally be utilized as a recruiting poll without having to worry about their reliability. While the AH's military performance was lackluster at best it managed to pull a startling upset at the beginning of the Battle of Asiago. Using ski based cable cars to haul guns up steep inclines giving them a 3 to 1 artillery advantage.
At this point the Austrian Forces were capable of beating the Italians and entering the Venetian Plain, possibly resulting in Italy withdrawing from the war. One of the main problems as that the Austrian Commander Conrad Von Hotzendorf and German Chief of Staff General Falkenhayn weren't on speaking terms and Conrad was unwilling to request assistance. My point of divergence is Conrad approaches Falkenhayn for German support, and receives it.
In real life the Austrians beat the Italians in the first phase of the battle, but were unable to follow up their victory and suffered counter attacks. With additional German forces, the Austrians manage to decisively beat back the Italians at Asiago resulting in central powers victory followed by an Italian rout.
The Italians suffer 200'000 Casualties compared to an Austrian 100'000 and German 10'000.
This results in Venice being occupied by the Central Powers and Italy requesting peace terms.
What do you guys think the peace terms would be, and how would this change the course of WW1?