Merlin

You want to see the world on fire?? Be sure to get Merlin as soon as possible!

Skill comparison
Attack Skill Ultimate skill Passive skill
 * A fireball drops from the sky, aimed at a random enemy. It doesn't chase moving targets, but the explosion can hit multiple enemies and it will often catch things before they get out of the way.
 * The attack gains 100 percentage points per weapon tier, for example a 4-Star weapon will get 600% damage. It hits one time per enemy.
 * This attack almost never misses bosses and it's a great player-killer, regardless of where Merlin is on the screen. It does often attack empty space when clearing normal enemies, though.
 * The party stops walking and a narrow beam of fire shoots straight forward, dealing many small hits in a row.
 * This looks like it should do decent damage, but it seems like not all attacks can hit the same enemy. It also misses often.  It's not a great skill.
 * Two balls of fire bounce around the screen, each doing 500% damage. Most targets will be hit at least once, and some can be hit twice!
 * This is an awesome skill in any game mode. It is useful in all circumstances.  It speeds up farming, kills bosses, kills players... It does everything.

Game Mode Comparison
Difficult Adventures or Challenges Easy Adventures or Challenges (for farming, grinding, or daily quests) Duels
 * Pros:
 * Normal attacks penetrate to hit multiple enemies.
 * Meteor helps kill bosses.
 * Passive Skill is awesome.
 * Cons:
 * He doesn't have much damage cancellation, and there are characters who can be optimized for higher damage.
 * Overall value: High
 * Pros:
 * Normal attacks penetrate to hit multiple enemies.
 * Meteor helps kill bosses.
 * Passive Skill is excellent, it makes everything faster.
 * Cons:
 * At high levels, Chiyome's passive skill helps clear missions a little faster. Merlin might only be the fourth best farming character, and you are limited to three characters in the party.  (Depending on what gear you have, Merlin may still be the best choice.)
 * Overall value: High
 * Pros:
 * Meteor wrecks players, even if Merlin is not standing in their line of fire.
 * The Passive Skill is also great.
 * Cons:
 * The Ultimate Skill usually misses or deals few (small) hits.
 * Overall value: High