Lethargy Mage is great against go wide aggro decks like Light and sometimes Nature. Hits Switch Duelist hard too. It's kind of bad against control being understatted.
Umber is great when you can get the 2 for 1. It ends up dead more than I like.
Trapper is a holdover from when Zombies and Anubians were popular. Not sure how worth it is to run now. 1m 2/2 guild isn't the worst.
I didn't like Contract Broker, the 1/1 usually died to something with more than 1hp.