Kraum, Ludevic's Opus

An effect that checks whether you control your commander is satisfied if you control one or both of your two commanders.

One opponent must cast two spells for Kraum's triggered ability to trigger. Two spells from different opponents won't cause it to trigger.

You can choose two commanders with partner that are the same color or colors. In Commander Draft, you can even choose two of the same commander with partner if you drafted them. If you do this, make sure you keep the number of times you've cast each from the command zone clear for "commander tax" purposes.