YMMV / Gem Craft

  • Goddamned Bats: Swarmers. These appear in large groups, and while weak, they're fast and require that you either use a Splash Damage/Chain Lightning tower (the latter of which chains less than half the time), or build lots of weaker towers and therefore making your strategy weaker to armored units (while spending money on towers). Furthermore, these easily distract your towers from attacking the stronger enemies. Thankfully, Swarmers do not do much damage to your Mana.
    • Chasing Shadows particularly enjoys sending waves of giants followed shortly or even directly by waves of swarmlings. Focus on the swarmlings? Giants will get through and do massive damage. Focus on the giants? Swarmlings will race through by the dozens and deliver a Death of a Thousand Cuts. If you have maxed out Giant and Swarmling Domination, Endurance mode will be effectively only Giants and Swarmlings.
  • Game-Breaker:
    • There a concept known as supergems, which are specially constructed gems to maximize damage output for as cheap as possible. Such a construction is practically the only way to hold back enemies for all waves in endurance missions (Gemcraft 0 or Labyrinth). The exact construction differs among the different Gemcraft versions, but the most common method is combining a gem with another gem that's two grades lower.
    • In the original, the pure red splash damage gem was this. One winning tactic is to make a top grade red gem to start with (restarting until you got one), and then starting 5-10 waves at once. Once you get to the maximum grade, a single red gem would be sufficient to kill the majority of the entire level, and the splash meant 10 waves could be dealt with as easily as one. Then, the additional mana from the early waves would give enough to create multiple additional top-level pure gems for rest of the waves, and the extra experience would give additional points for skills.
    • In Chapter Zero, supergemming Red/Orange combo to max speed, range and specials, and then setting it into trap was equal to setting a gem that skyrockets your mana that is self-sufficient for a good while and is probably your backbone in Endurance runs.
    • In Labyrinth, there are two common tactics. First is using the Red Bloodbound gem, which increases damage based on a percent of total kills. Next is the Lime/Yellow combination, which hits multiple targets with a damage multiplier.
    • The red gem in Labyrinth isn't a let down by itself, because it gains increased damage based on the percent of total kills, allowing it to deal extreme amounts of damage with enough kills.
    • In Chasing Shadows, a bloodbound/crit/chain hit gem enhanced with bolt is this. Crit adds a chance for multiplied damage, bloodbound increases the damage and special according to the number of hits, and the bolt enhancement makes mook armor ineffective, which means that with chain hit... you may instakill several waves at once, if you're playing a long level or endurance. This effect is increased if the gem is placed in a trap directly after a bloodbound/slow/chain hit gem trap.
    • Also in Chasing Shadows, the True Colors and Resonance skills. The former improves stats for pure-color gems and reduces the penalty on multicolored ones. The latter increases the stats on ALL gems. Using both it's possible to double or even triple your damage output with ease and still have plenty of points left for other skills, making beating the rest of the story super easy.
  • That One Level: Field U8 in the Steam version of Chasing Shadows contains a tome to unlock the Chain Hit gem. The problem is that the tome requires significant effort to accomplish - defeat 2700 monsters in the range of the tome chamber. For comparison, the next highest such requirement after that just requires 790 monsters. You will need to extend the level with difficulty modifiers and/or do extensive wave-enraging just to squeeze out enough monsters to fulfill the requirement.