Jack of All Trades, Rare 15/15/15
Mode 1:
Stock +21
Mode 2:
Attack:53
Mode 3:
Tower +37
Mode 4:
Wall +75
Mode 5:
Lowest Facility +2
I like it so far. Each separate choice is a little underwhelming, but that's perfect since the versatility is part of the value. It SHOULDN'T be as good as a Rare card that only does one of the effects.
Stock +6 (after cost) is spot-on.
53 attack is low for 45 cost, BUT since the cost is split evenly across all three resources, it's much easier to play than other attack cards of its caliber. Taking the versatility value into account and looking at this as a likely finisher that will be difficult for the opponent to prevent has me thinking it shouldn't hit any harder than it does.
Tower +37 can easily be another finisher. Most Tower+ cards cost bricks, and many more than 15 to gain past 30.
Wall +75 (twice the potential tower gain) seems appropriate.
Lowest Facility +2. This one stands out as seeming terrible. If one of your facilities is crippled such that you'd choose this option over all of the others, you're going to have trouble paying the 15 of that resource to begin with. At a total cost of 45, this should grant more than just two. I'm not sure what to propose in its stead, however. Perhaps raise any Facilities that are <3 to 3 and then gain two at random, or simply gain 3 random Facilities (which should favor the lowest ones first by overall game design). Compare what it is now to
Tubular bells which gives 3 Facilities for a cost of either 0 or (at most, depending on total individual resources) 45.
Edit: I suppose another option would be to leave the Facility choice as it is but include stock gain to refund part or all of the cost.