It doesnt matter whos responsible for defeating the battle, and theres no direct benefit to attacking a battle controlled by another player
Theres 2000 serialized poster cards out there, and 2000/1,500,000 is 0.00133 (repeating) and that rounds nicely to 0.1%
Commander: Tolsimir, Friend to Wolves
this will bring back the Loyal Retainers too, and you can then go around the block again
In general, I would look at these two factors when looking to include cards not of your tribe's creature type: Is this creature so strong that it, on its own, is generally stronger than my tribal creatures when they are receiving bonuses and/or empowering my other cards
Lorwyn Eclipsed supports five pairs based on creature types, but all of them could dip into vivid or -1/-1 counters cards, which almost acted like their own archetypes