On the topic of explosion nerfing:
the overall idea of reduced mana earning is fine by me but I do agree, however, with those you say that some little things need to be adjusted, namely, there absolutely should not be a situation when explode-destroying a single gem doesn’t yield any mana of the respective colour.
Sure, single gem exploders aren’t generally used for mana accumulation, but it doesn’t mean that their mana gathering ability should be totally annihilated. For example, today in Delves…my Gargolyle was one mana short and I used Arcane Golem to explode. One red gem was destroyed and no mana was accumulated.
Basically, there’s a choice of setting up an extra turn with explosion (while not earning the necessary mana) and hoping for some random cascades in order to be able to cast Gargolye right away or explode in a place with enough mana but not resulting in an extra turn and then hope AI won’t damage you too much before it your turn again…
( Well, third option is not to explode again, but sometimes it really is a situation of who will manage to cast the damage dealing spell first).