i believe it goes 100 > 300 > 500? > ??? (it may be 1000 or less) >???
i find these type of schemes total rip offs, the scheme is common for all these card games and the pay off seems to suck for most of them (i say most, but i've found that you can get better pulls from tickets in Legends of the Cryptids and Galaxy Saga compared to RoD and RoB, so maybe their version of climbing packs have better results)
keep in mind that I'm speculating beyond the second one which is 300
more importantly, you're not guaranteed to even get an SR once you reach 5 and get a sheet.
the first time i spent cash was on the stamp pack, where you get 12(?) cards, a sheet, and 1 stamp. the stamp landed on blessings, but i was extremely lucky and got a MR from the 12 pack. extremely lucky, seeing how the premium packs mostly give rares. at the time when i barely had any rares, it was worth it, not that I'm finishing of my SR and looking to get MR's, not so much.
but I'm a free player now and i haven't made any more purchases since the first one, so take what i say with a grain of salt
totally random but landing on the cards is probably harder
i think the one-time purchase of the stamp pack for 1000 gems is a good deal if you're going to pay.
the climbing pack 1st tier is good due to getting a potion along with a card, where you might get lucky. which i totally forgot i did (so i actually made two purchases), i pulled what was my first Demonsword from that pack. that was a very lucky day which i've never been able to pull off with premium tickets since (although i did get a Mage Queen from a premium during the 30 day login).