General overview

While all players get Cliffheart for free at the beginning of the game, she's not a very good early game investment for players who just need a basic puller. (Rope is cheaper and pulls just as well.) She sets herself apart in situations where she's being used to more interesting ends, with crowd control and Arts and True Damage. If you're willing to take advantage of her strengths, she's a great investment for both old and new players.

E2? She doesn't need it, but for advanced players, masteries increase her shift strength and give her some other benefits.

Talents

Cliffheart's talent gives her an ATK/DEF buff when she's not blocking. She will rarely need to block enemies, so this talent will be active more often than not.

Skills

S1 (Chain Hook) is the usual auto puller skill, although she deals Arts damage when she pulls.

S2 (Binding Chains) is her more interesting skill, which pulls 2 targets in the 3x3 square in front of her, dealing True damage and stunning them. This skill is a great multitarget pull, but it's also a pretty spammable source of True Damage and stun. The range is also very wide, allowing you a lot of flexibility with where you put her. I personally find the stun to be the most useful aspect of this skill because you can strategically use it for crowd control or enemy disruption.

Masteries

Both skills go from pull force 1 at level 7 to 2 at M3. S2 gets an additional target at M1, which is a nice breakpoint. If you use S2 for the stun, go all the way because M3 doubles the stun time as well!

Modules

Module X deals Arts damage proportional to the distance that Cliffheart pulls them (800 per tile). The upgrades slightly increase the multipliers on her talent. This module isn't particularly useful unless you're using her for DPS.