I’ve been waiting for the red set to cycle around, but now that it’s here I’m not sure which BB to get.
I have:
So I guess statically I should be getting a SOI BB, but I’m missing all of my rare burn spells.
What would YOU do?
A lot of people are holding off on SOI until the exclusives are able to be looted from them (or are waiting to see if the next expansion will be added into it, like OGW was for BFZ).
I’m never sure which to get so I won’t answer, but I figured this may factor into your decision.
I’d get the Red box just to so you have a chance of getting the Zendicards that aren’t currently available .
On a side note, how did you figure out what % you have?
Honestly, I’d say wait for the next group of cards to drop then go after SOI. Though, going after the color lot makes a lot of sense, especially if that color is particularly low in your collection.
For me the best way to decide is to filter cards by rarity including only rares and mythics.
Then you look which ones you are missing that you REALLY want/need and keep note.
Do it for each collection and each color and decide which big box is more valuable for you.
I was super excited for the red cards to be available as I had recently procured Nahiri and was gunning for Saheeli (which I was ever so fortunate to obtain this morning)
I had bought the blue card big box and had some decent scores with Day’s undoing, Thopter Spy Network, Oath of Jace, Prism Array and Exert Influence, The 4 Red BB’s I had purchased had left a horrible horrible taste in my mouth
Molten Vortex
That was it
The rest were all dupes and I needed over 12 mythics and Rares
Like 3-4 dup Mythics and easily 14 dup rares.
Heartbroken
Don’t know how many I bought from Green card BB to try for Ulvenwald Hydra
But was equally dismayed.
To figure out percentage, go to library. Add a filter (by set, color, etc). Then on the filters tab, it’ll show you how many of those cards you own. Next check the “show all cards” for total available. Do math. 
I know drop rates aren’t super awesome and is a continuing complaint on these forums, but I’ve got 9/40 rares and 0 mythics for red. So I think my chances are pretty good, lol.
Concerning exclusive cards, do they become non-exclusive at the release of the next set?
Historically, yes.
When is the release of the next set?
Based on current drop rates, I would only buy packs if I were ready to gamble hard-earned money for a boat-load of dupes. Then again, there is a slight chance of getting something good. And of course an even slighter chance (still possible) of getting like 3 or 4 good cards.
This is worse than a bloody Casino. They should at least increase the Runes you gain from dupes to lessen the blow.
I’m just waiting for them to offer some other option for dupes. then everyone rage about all the runes they’ve turned in, lol
I had really good luck with the red big box. Tyrant of valakut, abbot, brutal expulsion, couple of dupe mythics and some other rares
Well, I got the red box.
only 2 rares and 1 mythic, all new though. (avacyn’s judgement, avaricious dragon, goblin dark-dwellers)
red cards owned went up to 70%. 58/71 were dupes… 
Sidenote: is Devour in Flames any good? 5 damage, give opponent 5 mana, costs 3
Also, avacyn’s judgement? playable? seems like it…