The 10x and 40x have bonus draw rates for higher star characters than single packs (YMMV on the value of the draw rates, but that’s not my problem
), and the 40x comes with a legendary token, the value of which is entirely subjective to the buyer as well. It’s all up to you if those perks help, and as to the point of the deal system not being a super deal: okay. You’re getting 200 HP off, plus the perks of the better draw that comes with bigger packs already. Hero points are where the most cash is made for the game, and it’s always enticing to think “For just a few dollars more…” and it’s simple marketing. At least the sales are kinda sorta decentish. The other option is to grind, grind, grind for placement and the freebies
The real cost in those packs is in the HP for rostering and the iso for leveling, but there’s no need to worry about that when the covers are flying, right?
Negative. You might get the Legendary in said vault if one is available, but you are not guaranteed anything good from a vault 40-pack. Your odds are just more plain.