The game has too many resources and it is overwhelming for new players - I suggest to remove elemental crystals from the game altogether as it serves very little purpose:
New players are the only ones constrained by crystals (e.g. I have 4 magic heroes at 59 and still have over 3k magic crystals; and even that’s so low compared to the others because I had already played a lot before Magic element was introduced), but even without the crystals new players cannot level up heroes as and when they please because Hero Medals are a major bottleneck at promotion points (9, 19, 29, etc), even if they had the coins (new players are also severely handicapped by coin shortage).