I feel that being able to upgrade pillars but nothing else with coins seems a bit unbalanced, or less fun knowing that you can upgrade a pillar with coins and you don't need to obtain anything to do so except from coins which is easily obtained. Although, I thought of an alternative route which involves being able to obtain pillar upgrade tokens. I haven't fully thought this through, but I think that it would be a nice addition and would make it more of an achievement getting a token, instead of just noticing you have coins and knowing that you can upgrade any pillar without having to do anything else.
I had another idea that these pillar upgrade tokens can be sorted in 3 categories, basing of the material, spiritual and cardinal pillars. As in, you get a cardinal upgrade token and you can upgrade entropy, gravity, time and aether pillars, but not the other 8 elements. The cardinal upgrade token can upgrade the cardinal pillars, material upgrade token upgrade material pillars etc... Quantum pillars can be upgraded with ALL 3.
*IMPORTANT NOTE: When I talk about pillars, this includes pendulums also.
