I was surprised when the webspinner vas really good, a 1/1 that basically has death rattle give a free minion is awesome. Deaths Bite is insane, two 4 damage swings is already value for a 4 drop card and a free whirlwind gives you card draw, armor and even can proc grommash for a huge 14 damage to the face with 8 mana woo!
I've had some pretty good times with Avenge in Arena. It''s much more common to have a bunch of minions around than in contructed. Since it's so cheap you can stick a taunt or something down, and even a Recruit becomes a threat that needs dealing with.
Playing Shade of Naxxramas is similar to playing Shade of Naxxramas?
At first my favorite Nax card was Nerubian egg, but now I like cards like Webspinner, Death's Bite, Mad Scientist, and Sludge Belcher alot more. Anywho, I love how a few cards have had a significant impact on the meta. Good job Blizzard, Nax was a success in my book!
Worth mentioning that Feugen has great stats for a vanilla minion which makes a grading of F quite misleading. If your arena legendary pick is between Feugen and mediocre to terrible legendaries i.e. Lorewalker Cho, The Beast, Nat Pagle, Feugen is a great pick similar in power level to Chillwind Yeti.
For me Mad Scientist is good only in mage deck. Hunters and Palas secrets are more tactical. I don't want exploding trap when enemy has 1 minon on board, or combo frost+misdirect, or resurrect 1/1 Recruit. Mages secrets are more universal and cost 3 mana so Scientist is the best choice for them.