Gear: The most important aspect of this game.
Basically items that you can equip to characters (max 3 per character) that give them bonus stats/effects. Surf around the wiki to see all the possibilities. Fusing levels the gear up and increases the stats/effects they grant. Evolving can be done on a gear that is at level 10, after which the gear gains a star and can be leveled up 10 times again after which it is consider maxed. Extra copies should be shattered for shards, but more shards are granted when the gear is evolved or when its fully maxed (being fully maxed grants more than only being evolved). Bottom line is: keep 1 copy of every gear, evolve/fully max them, then shatter extra copies.