My group has done upwards of 10 boss runs, each time getting Tanihwa, with "lizard" and "great warrior", we have added as many runes as possible to increase difficulty, including "Supreme Might" and "Might", but we have yet to see any drop whatsoever, please message me if you have other information. -- Mishli 1-08-09
Jan 12th '09 Update: "The requirements to obtain treasure in MMM while using "Liquidation Team" have been adjusted." Whatever that really means.
Setting multiple "Family", "Size", and/or "Behaviour" runes may cause the NM to be an elemental. For instance, setting Beast, Lizard, Vermin, Great Warrior, Tiny Warrior, and Motion resulted in Fulmen (Thunder Elemental).
Adding both a size and a behavior rune will result in multiple possible drops, but also nightmare TP moves. i.e. Great warrior + Stillness Tanihwa uses Nightmare Bugard TP moves instead of just Bugard moves. On the other hand, NMs like the flytrap tiny warrior + stillness Metshaldjas don't get any nightmare TP moves and make a nice alternative to death by fungic koti.
Every item has the hidden effect of giving you beast, plant, vermin, or lizard affinity. For example Ermine's Tail has beast affinity which allows you to intimidate lizards, but you may be intimidated by plants. For items with no hidden effects noted, check the family rune needed to get them to drop and that's the affinity you gain.