The hobby challenge for the last tournament I went to (the St Valentine’s Slaughter) was to bring along a treasure marker themed to the event and your chosen Master. In my case that was Sonnia. I decided to make my theme instead be ‘a marker I’ll actually use again’. The Henchman did generously suggest that the locked box could be symbolising Sonnia’s quest / penchant for forbidden lore, but I think he was just being nice. Anyway, of a public vote I rightly came in fourth (of four entries) with zero votes; the other three were really good and can be seen here.
The marker itself is a treasure chest from the Ogre Kingdoms Ironblaster kit.
Next on the painting table: the Illuminated (still).