Whoa that’s a good card! It’s like Mad Scientist value. While it’s better in a mass secret deck like wild secret mage, I could see it used to tutor out Ice Block when combined with Ice Barrier in wild.
Looks good, but given Bellringer Sentry saw zero play I'm not sure this is a definite hit in standard (yes I'm aware that was Paladin and Paladin secrets are WAY worse to cheat out than mage or hunter secrets!). Wild may be a different story though, especially as Ice Block is such a reliable trigger for this.
Obviously best in mage if you can somehow curve it out nicely, where it's 2/4 + 3 mana secret for 3 mana (basically secret with a free 2/4 body). Coin into Kirin Tor Mage + Secret into T3 Masked Contender will be quite nice. Hunter may be the best class for it though for consistently curving turn 2 secret into turn 3 Contender.
Probably not worth it in paladin though; 2/4 for 3 plus a paladin secret that's conditionally dependent on already having a secret in play just isn't worth. Only reason it's more viable in hunter is that they'll usually have a turn 2 secret thanks to their spellstone.