So allow me to explain!

S1: Enhancing artificer skill.

Devices passively give defense up to the operators they’re pointed towards. You can see the numbers in the “summon” section of her profile.

On activation, Nasti gains Atk and Def up, and attacks targets equal to block count: devices increase their def boost and give +1 block, loosing durability while skill is active.

Gain 1 device on activation.

S2: Battery artificer skill.

Devices take effect only on activation. On deploy, they start with only a few of their maximum 8 “charges,” represented as HP. Until the skill is activated, they gradually gain charges over time.

On skill activation, they gain additional charges (see summon details) and begin expending charges every .5 seconds for 4 seconds, giving SP and barrier, until they are exhausted, at which point they disappear. Meanwhile, Nasti stops attacking and gains a larger amount of barrier at the same intervals.

Gain 1 device on activation.

S3: Unique skill, brings RA mechanics to other stages.

On deploy, the first device deployed toward a valid grid square designates that square as a high ground tile build point. The device begins to passively charge the build point’s SP over time: when the bar fills the first time, it becomes a special high ground tile like the deployable ones in RA. Operators can be deployed there and receive a passive Atk and Def increase, and the tile blocks 1 and can take damage: if the tile takes damage, devices working on it will use their hp and restore its hp in parallel to their construction function. Devices will continue to contribute SP, filling the bar up to 2 more times, each increasing the magnitude of the Atk and Def buff. At maximum stacks, the tile will remain even if Nasti is retreated.

Only one special high ground tile can exist on the stage.

On skill activation, Nasti will gain a significant Atk and Def buff: devices will build and repair the tile at double speed for the duration.

S1: Off-skill defense up is dependent on Nasti’s elite level (E0: 17%, E1: 20%, E3: 25%). On skill defense up is dependent on Nasti’s Skill Level (46% M0 -> 55% M3).

S2: Only barrier scales with skill level (4% M0-M2, 5% M3). Devices start with 2HP at E1, and 3HP at E2: always gains 1 HP/4 seconds and 1 HP at skill activation.

S3: persistent Atk and Def buffs from special high ground tile scale with skill level from 15% per stack (max 45%) at M0 to 20% per stack (max 60%) at M3. High ground tile HP and Def scale (with skill level?) to a maximum of 4150 HP and 385 Def.

Each stage of building/upgrading takes 50 SP, and devices contribute 1 SP/s at base. This means an upgrade level takes:

50s with one device

25s with 2 devices or one device while skill is active

12.5s with 2 devices and skill active.