I know in the water temple, its the first plant you come across AFTER you get the fire ring (the one with the crab as it's side mob) that usually drops a fire gem and a mana ore. vs the last plant who only drops a feather gem. But yeah I've been noticing the same things you were, how some of the monsters tend to drop certain gems. The mob drop tends to be fairly certain for each mob in each area, but the rng is wether the game drops items off the mob or not.
If you didn't look, I've re-mapped my magic ring getting which overall saves time/mana to help the run progress more smoothly. The 1st one saves mana more-so than time I feel with the grabbing behind the save point, and the other one past the first ogre there I believe is a shorter detour than the chest in poison valley. (plus you aren't being bombarded by poison the whole time)
I am still on the ropes as to whether it's worth crafting material arrow, or just saving the stones for a lvl 3 attribute gem later on in the game. Fireball probably does just fine and is a cheaper spell so I might be able to farm my golems faster, or a goblin faster (if they drop a forest gem) for the remainder of my route. Cause really the only thing i use material arrow for is faster dps on the earth golem (of which i don't think it does much) and to open the magic only doors in the lava fields.
If you didn't look, I've re-mapped my magic ring getting which overall saves time/mana to help the run progress more smoothly. The 1st one saves mana more-so than time I feel with the grabbing behind the save point, and the other one past the first ogre there I believe is a shorter detour than the chest in poison valley. (plus you aren't being bombarded by poison the whole time)
I am still on the ropes as to whether it's worth crafting material arrow, or just saving the stones for a lvl 3 attribute gem later on in the game. Fireball probably does just fine and is a cheaper spell so I might be able to farm my golems faster, or a goblin faster (if they drop a forest gem) for the remainder of my route. Cause really the only thing i use material arrow for is faster dps on the earth golem (of which i don't think it does much) and to open the magic only doors in the lava fields.