There are the following:kman123 said:For some reason I only got two endings...did I miss something to get the third ending?
Destroy, Low War Assets
Destroy, Medium War Assets
Destroy, High War Assets
Control, Medium War Assets
Control, High War Assets
Synthesize, High War Assets
In order to get the third choice you have to have a high level of war assets.
War assets achieved are based on the choices you've made throughout the three games as well as in the ME3. For example, if you gave the collector base to the Illusive Man at the end of ME2, it is going to be harder to get the synthesize ending. If your choices led to the destruction of the Geth and Quorians, it is going to be harder to get the synthesize ending. If you had lots of your ME2 crew die at the end it is going to be harder to get the synthesize ending.