Irisviel’s defining trait is the Guts buff she grants to the whole party, which is built-in to her Noble Phantasm. Aside from these, she boasts high burst healing abilities, being able to heal up to 9000 HP to a single target at max potential. Possessing an Invincibility skill herself, it means that she will be fairly easy to keep alive.
Her biggest drawback, however, is the below-average NP gain. Her NP gain buffing skill only brings it to a normal level even when maxed, resulting in a lower healing output than what is expected of her. Her first skill, which increases healing, also has a rather long cooldown, meaning that she will have some downtime between her healing bursts.
Pros
High healing power
AoE Guts
Survivable
Cons
Low NP gain
No other functions except for healing and Guts
Long downtime
Strategies & Tips
The main problem with using Irisviel is that she needs set up for to patch her NP gain. These include help from Craft Essences (such as Prisma Cosmos), and Servants (such as Tamamo no Mae). The Guts can be used as some sort of hard defensive skill; however, she will need to heal the team afterwards, so timing is rather important to her usage.
Her Invulnerability skill should be used to protect her in crucial turns, though it is also possible to use it as a way to enhance her NP gain in order for her to keep up.
Noble Phantasm
Song of Grail heals the whole party, and grants them a Guts effect (magnitude increases with Overcharge). Irisviel’s Noble Phantasm is the most important part of her kit, defining her usage in higher-tier content. Unleashing this NP should be her top priority, especially when the Guts effect is needed.
Irisviel and Tamamo’s combined healing should be able to easily sustain the party through most stages. Tamamo’s cooldown reduction and NP charge also helps mitigate some of Iri’s biggest weaknesses. On the other hand, Iri’s Guts effect serves as a hard defensive option - something that Tamamo notably lacks.
Merlin’s powerful heals, NP gain assist, and Invincibility skill are all appreciated by Irisviel (although in this composition, his third skill is generally somewhat wasted). He allows a much faster NP cycle for Irisviel, though it is arguable whether Merlin or Tamamo has the edge in this.
Irisviel’s low NP gain means that she benefits greatly from Zhuge Liang’s skills. His defense buff also helps with damage mitigation, and his Noble Phantasm is able to buy more time for Iri to fill her NP gauge.
NP Charge Irisviel’s low base NP gain means that most other alternatives (i.e. Arts performance up and NP gain up CEs) are less effective. As such, Craft Essences with fixed NP gain per turn, such as Prisma Cosmos, is more or less her best choice to increase her performance.
Arts Up / NP Gain Up While far less effective than fixed NP charging CEs, these still help her NP gain, and should be considered as an alternative to the former. Arts up is generally better in this regard, as Irisviel already possesses an NP gain buff in her second skill.
Starting NP (Kaleidoscope, Imaginary Number) Should be used in fights where Irisviel’s Noble Phantasm should be used early on (the most notable example is the Goetia bossfight in the chapter Salomon).
Max Bond Level CE
work in progress
Stats
Lvl
HP
ATK
Base
1,996
1,372
Lv40
7,194
4,777
Lv80
12,476
8,237
Hidden Stats
NP Charge (ATK)
0.42%
NP Charge (DEF)
3%
Star Weight
50
Star Rate
10.8%
Death Resist
34.5%
Alignment
Lawful, Good
Attribute
Sky
Traits
Servant, Humanoid, Divine, Weak to Enuma Elish
Noble Phantasm
Song of Grail (Rank B)
Recovers party's HP. [Overcharge]Grants Guts status for 3 turns to all allies.
Rank
B
Classification
Magic
Type
Arts
Hit-Count
uff0d
Lvl
Crit Rate -
Charge
Revives with
1
2000 HP
100%
1000 HP
2
2500 HP
200%
1500 HP
3
2750 HP
300%
2000 HP
4
2875 HP
400%
2500 HP
5
3000 HP
500%
3000 HP
Skills
Upgrade Priority
Resolution of Commitment A Increases Irisviel’s healing power for one turn. This skill is extremely potent when used, due to Irisviel possessing two heals - one from her Noble Phantasm, and another from her third skill. This skill is usually most beneficial when used alongside her Noble Phantasm.
Infant of Nature A Applies an Invincibility buff on Irisviel, and increases her NP gain for three turns. Though it is nice in concept, the NP gain increase (capping at 30%) is too small to make a major difference for Irisviel. As a result, this skill is mostly used for the Invincibility function.
Magic Medicine A A standard targeted healing skill, with a 3000 HP heal and 5 turn cooldown at max level. While this skill is generally decent, it won’t really be significant unless paired with either her first skill, or her Noble Phantasm.
Priority: 1/3/2
Resolution of Commitment A
Available from the start Increase own Healing power for 1 turn.
Lvl
Heal Power +
Cooldown
1
30%
9
2
32%
9
3
34%
9
4
36%
9
5
38%
9
6
40%
8
7
42%
8
8
44%
8
9
46%
8
10
50%
7
Infant of Nature A
Unlocks after 1st Ascension Grants self invincibility for 1 turn. Increases own NP generation rate for 3 turns.
Lvl
NP Rate +
Cooldown
1
20%
8
2
21%
8
3
22%
8
4
23%
8
5
24%
8
6
25%
7
7
26%
7
8
27%
7
9
28%
7
10
30%
6
Magic Medicine A
Unlocks after 3rd Ascension Recovers one ally's HP.
Lvl
Heal
Cooldown
1
2000 HP
7
2
2100 HP
7
3
2200 HP
7
4
2300 HP
7
5
2400 HP
7
6
2500 HP
6
7
2600 HP
6
8
2700 HP
6
9
2800 HP
6
10
3000 HP
5
Class Skills
Territory Creation B Increases damage of unit's Arts cards by 8%.
Goddess' Essence C Increases damage by 200 and resistance to debuffs by 20%.