Sage, Legion, Tribunal hmm... This was one I was originally looking at until I got Tribunal as that Random Series 4/5 card last month with the Red Guardian Cache. Legion is still one worth considering as one of the more unique tech options in the game. But Legion is also Series 4 so not that expensive to get with Tokens, likewise Tribunal supposably going to Season 4 as well make it less valuable as well. Tribunal is good, though most of it's big combo decks need other Series 4/5 cards to pull off (Phoenix Force, Ravonna, M.O.D.O.K. to name a few of the archetypes Tribunal goes into). Good cards, but also not amazing cards, and also cheaper cards to get now as well.
Which leaves Sage. The obvious comparison is Wolfbane, which can hit 3/7 when played to a full location. Whilst Sage can hit a 3/14, the catch is to hit the potential, you need to go to a place where your opponent has played a lot of different power minions. Never great to build a plan around what your opponent is doing, you can run White Widow to at least place a -4/0 in the location alongside a 2 power, but if you are planning to pair Sage up with Wong. That's your 2 already covered. Silver Surfer and Mr. Negative are the decks most likely to consider Sage. It is a lot of potential burst power on the final turn that your opponent has to be weary of. I just have some concerns on cards that are dependant on your opponent, maybe Jean Grey is the sauce that pushes Sage over? I Think it's a wait and see initially on how Sage fairs before going in.
And the last thing to mention is with a series drop coming soon, all the caches between now and that series drop are going to be worse because there is the off chance you might get one of the cards that's about to drop down series. It's a low chance sure, but it is still a chance.