Hey guys,
The Overall Concept; Rather than just renting X power for Y time and it later expiring without a trace... You instead gain a portion of that power to help you work towards a permanent version in future via much more manageable payments, and still reap the benefit of the full item of choice along the way (for a time).
Regarding some of the questions, will first refer back to the news notes:
You can purchase multiple Rune Packs at once, but bonuses from other packs do not stack with bonuses from other fragile or permanent items (eg., you cannot buy multiple "Volume of Conclave" to gain multiple +120 stat bonuses simultaneously, or stack them with unlocked 'non-timed' bonuses of the same kind.
As mentioned, the non-rune bonuses
DO NOT STACK (neither with itself [double rent] or the permanent version) - so if you already have the permanent version of X unlocked, renting X will provide no additional benefit other than the permanent 'extras' you get with the purchase. Same can be said about renting a power twice at the same time (which I assume would refresh the duration, not 'stack' with it - but you would still get the permanent extras per each purchase).
As for Temporary Runes;
If I buy 6 Fragile Runes of Level 8, will I receive 2400 Crystal Chips? Or is that a non-stackable bonus?
You can rent as many as you need at any time, and gain the extras with each purchase, so yes, if you were considering multiple level 8 temporary runes for a month, you would get the 400 crystal chips per rune rented to help you work on your own permanent runes (or whatever else you choose to do with them). TLDR; Renting 6x8-Temp runes would indeed net you 2400 crystal chips.
Meh, except for the 4th page of Mage's diary, rest is not even that rare. Maybe introduce the next tier in a promotion like this?
As said in the news, new timed artefacts will also be considered in future, so keep your eyes open if the system appeals to you -- it is early days yet!
Regards,
Mhul
PS. Pretty certain the rubies are not a mistake