Before I begin, I would like to talk about the interaction between Soldiery Tomes and Allied Seals.

To get a piece of i110 Soldiery equipment, you'll need both Soldiery Tomes (weekly limit) and Allied Seals (can be farmed ad infinitum). This means even if you can farm a billion sands using Allied Seals, you are still tied down by the weekly limit of Soldiery Tomes.

Into the main topic, I hope we can have such a system for Coil as well.

Each chest inside Coil always have the same loot table, so I propose a system where we can spend a type of currency, to "lock" a certain chest to drop the exact loot from its loot table that we desire, instead of praying that the loot you wanted to drop. (This is analogous to Soldiery Tomes in the above).

Now for this currency, I would suggest removing the lock out from Savage Coil, and each clear from Savage Coil will provide every player a certain number of this currency, thus if the players are good enough, they can farm this currency ad infinitum (This is analogous to Allied Seals in the above).

This way, if a group is good enough to clear turns from savage coil, they will be able to dictate what loot that will drop for every turn in normal coil, and since normal coil can have 8 chests in total only, even if you farm Savage Coil crazily for the currency, you are still limited on how much you can spend weekly (See Soldiery Tomes and Allied Seals interaction).

I would think the luxury of letting players pick what they want from chests in normal coil, would be incentive enough for more people to attempt Savage Coil.

Hope what I describe above is clear enough!!