FGO NA Ciel Build Guide: Skills, Best Teams & Is She Worth Summoning?

Mysterious Executor C.I.E.L. is a limited five-star Moon Cancer who stands out as a single-target Buster damage dealer with an unusually flexible playstyle. Her kit revolves around taking control of the Command Card hand, creating reliable Brave Chains, and combining powerful critical attacks with steady NP recovery. Rather than relying entirely on her Noble Phantasm, Ciel can switch between Buster bursts, Arts-based charging, and sustained card damage depending on the situation. This makes her particularly effective in boss fights, challenge quests, and irregular farming stages where a conventional three-turn looping setup may struggle.

Ciel Overview

Ciel normally deals neutral damage to many classes, but her Executor (Bow) A passive gives her offensive class advantage against Saber enemies. She also has passive Critical Strength, Debuff Resistance and 500 HP regeneration each turn.

Ciel’s Skills

Skill 1: Human Magical Energy Plant A

This skill grants Ciel 10% NP every turn for five turns. At Level 10, it also restores 1,500 HP per turn, increases Debuff Resistance by 50% and raises Buff Removal Resistance by 100%.

The effects last five turns on a six-turn cooldown, giving the skill excellent uptime. The healing helps Ciel maintain the full-health condition required for her strongest critical buff, while Buff Removal Resistance protects her setup during difficult quests.

Skill 2: Phase-Gliding Blade B+

At Level 10, this skill provides 30% Arts effectiveness and 30% Buster effectiveness for three turns. It also grants two separate Critical Strength buffs:

• 50% while Ciel has at least 50% HP;
• another 50% while she is at full HP.

Both effects can activate together, giving Ciel up to 100% Critical Strength before passive bonuses and external support.

Her Arts Cards reduce enemy healing, have a 30% chance to reduce the enemy’s NP gauge and remove Guts. Every Buster Card used while the skill is active restores 10% NP, including her Buster Noble Phantasm.

Skill 3: Idea Blood B

Idea Blood is the skill that defines Ciel’s gameplay. It temporarily prevents the other two frontline Servants’ cards from entering the deck and reshuffles the Command Cards. The result is a full hand containing Ciel’s five normal cards.

It also charges her NP gauge by up to 50%, grants 100% DEF for three hits over three turns and restores up to 2,000 HP whenever she is attacked, up to three times.

Because Ciel can guarantee her own cards, she can create an NP Brave Chain, select multiple Buster criticals or use an Arts chain without depending on random card distribution.

Noble Phantasm: Code: Original Sin

Ciel’s single-target Buster Noble Phantasm applies Sure Hit and Ignore DEF before dealing damage. It deals 150% special damage against Demonic enemies and restores 20% NP after use.

Its Overcharge effect grants 30% to 60% NP Strength before damage. Combined with Skill 1 and the Buster effect from Skill 2, using her NP can provide:

This fixed recovery allows Ciel to recharge consistently even though she uses a Buster Noble Phantasm.

Best Skill Upgrade Order

The recommended order is:

Skill 3 → Skill 1 → Skill 2

Skill 3 should reach Level 10 first because the 50% battery greatly improves Craft Essence and support flexibility. Skill 1 comes next for stronger healing, resistance and shorter cooldown. Skill 2 remains important for damage, so the ideal final build is 10/10/10.

Best Ciel Teams

Ciel + Koyanskaya of Light + Summer BB

Ciel uses Idea Blood to generate five of her cards, then Summer BB uses Faceless Moon to preserve that hand. This allows Ciel to repeatedly use her own cards for several turns instead of losing them after the first shuffle.

Koyanskaya supplies the critical stars and Buster support that Ciel lacks. This is her signature setup for irregular farming nodes and short challenge quests.

Ciel + Double Koyanskaya of Light

Double Koyanskaya provides 100% targeted NP charge, large Buster buffs, Critical Strength and skill cooldown reduction. This setup allows Ciel to reuse her skills quickly while repeatedly generating NP through her Buster Cards.

It works well in short boss encounters where Ciel can combine her NP with guaranteed critical cards.

Ciel + Koyanskaya + Merlin

Merlin offers healing, Critical Stars, Buster effectiveness and team protection. His healing also helps Ciel return to full HP so both parts of her critical buff remain active.

This team is slower than the Summer BB setup but safer in longer challenge quests.

Strengths and Weaknesses

Is Ciel Worth Summoning?

Ciel is worth summoning for players who already own Koyanskaya of Light, enjoy card-based critical strategies or frequently farm irregular 90+ and 90++ nodes. Summer BB owners gain even more value because card locking turns Ciel’s one-turn guaranteed hand into a multi-turn damage setup.

She is less important for accounts still missing core supports such as Castoria, Koyanskaya or Oberon. Players mainly seeking a conventional AoE farmer may also find a wider use for other summer Servants.

Ciel works at NP1 because her card control, battery and critical mechanics do not depend on NP level. Higher NP levels mainly improve her single-target Noble Phantasm damage. She is a powerful and distinctive damage dealer, but her value rises significantly when the account already has the supports needed to supply stars and Buster buffs.