Scathach-Skadi (Ruler)

Skadi’s skills are unique in that they have two potential uses. One use is to boost Quick and NP gauge in order to enable looping, and one is to boost Buster Critical damage. In both cases, all three skills will be burned on the first turn on the target to ensure that they can take advantage of the bonuses for all three turns. The only exception is her third skill which gives a flat one-turn star bomb, NP charge, and absorb rate up. A Master may strategically decide to hold off on that skill until needing a burst. Suggested skill level order is the third skill to get the most NP gauge charge possible, then the first for better scaling, and then the second.

• Primordial Rune (Midsummer) consists of two vastly different but important effects. The first is the standard targeted 50% Quick buff common in Scathach type Servants. This part is what will enable looping. The second part is a massive 100% boost to Buster Crit performance for 3 turns for that Servant. On a Berserker or another type of Servant with 3 Buster cards, this will lead to massive Critical hits if they can get the stars to themselves. This skill is best leveled 2nd, and to max to maximize its damage.
• True Summer's Ice Cream C has much smaller boosts than Primordial Rune (Midsummer), giving 15% Quick up instead of 50% and 15% Buster damage up instead of 100% Buster Critical up. However, it also gives a nice boost to Attack. Outside of its general damage steroids, it does provide a consistent means of Critical stars for those using Skadi for Buster Critical purposes. For those using her for Quick looping, these Critical stars will be rather trivial due to the large amount generated from Noble Phantasms. This skill in theory could be left at level 9 due to its small amounts of scaling, and should be leveled last.
• Lost in Thought Late on a Summer's Night A+ provides two crucial benefits: Up to 50% Noble Phantasm charge and a large boost to Critical Star absorption for a turn. Should a Master be interested in Quick looping, they would want to use this either on the first turn to give an initial boost to NP gauge, or on a turn to fill in the missing gauge after a Noble Phantasm, depending on the math. If they are more interested in Buster Crits, this can be used any turn that there are not many stars available on the field for the Buster Critical Servant. It will not only redirect all the stars to their Buster cards, but also give 15 more Stars for that Servant to play with. As a skill with a scaling charge, this is best leveled first and to max.

“Hm? What is it? Did you really bring ice cream? You do not have that much free time… No, fine. All right. Good way of thinking. Then I shall eat it. Ufufu.”

The summer is the perfect time for ice cream, and who better to celebrate it with than the queen of ice voiced by Mamiko Noto! Taking up the Ruler class, Skadi becomes a premiere AoE Quick Damage and Support Servant, and also serves quite well for Buster situations as well.

Skadi has three unique ways to use her. The first is to combine the Quick up of Primordial Rune (Midsummer) and True Summer's Ice Cream C with her NP charge of Lost in Thought Late on a Summer's Night A+ to enable AoE Quick Servants to loop, some with a Black Grail. The second is to create a Buster Crit machine with Lost in Thought Late on a Summer's Night’s star absorb skill for Buster cards, True Summer's Ice Cream’s Buster boost, and Primordial Rune (Midsummer)’s massive Buster Crit damage boost. The third is to use her for fairly decent damage herself with a powerful Noble Phantasm, Gate of Aegir, which deals extra damage to Lawful enemies.

Her biggest challenge comes down to her survivability. She also requires fairly heavy investment in terms of other Servants for looping purposes. She also lacks a longer term Crit absorb skill.

The queen of ice is a worthwhile addition to any Master interested in looping with Quick cards, or with dealing critical hits on their Buster cards. Sei (Berserker) is just drooling with glee waiting for her to drop.

Quick Support

Ruler Skadi has two skills which boost Quick card performance, as well as a 50% gauge charger. By using Ruler Skadi, a support Skadi, and the original Skadi or Oberon, many AoE Quick Servants can now use three Noble Phantasms in three turns while using a Black Grail. When this occurs, it tends to result in quite large amounts of Wave 2 damage, as well as generating a large amount of Critical stars.

Buster Crit Support

Surprisingly, Ruler Skadi is an excellent Buster Crit support. Her first skill offers a whopping 100% Buster Crit boost, the equivalent of two Koyansakaya of Lights combined. In addition, she can passively generate 15 Critical stars a turn with her 2nd skill and immediately generate 15 stars with her third, all which can be directed at the Buster Critical Servant of her choice with her third skill’s absorb rate boost. At a maximum of 5000%, whoever receives this will get the Buster Critical stars, even if they are a low-absorb class like a Berserker. 

Damage

If a Master wishes to make use of Ruler Skadi for damage, they will need to pair her with a support Ruler Skadi and a Caster Skadi at minimum. But when one adds in a Nero Bride or Oberon on top of that, she can hit some rather nice numbers serving as a damaging Servant. She also has a supereffective trait against Lawful alignment enemies, boosting these numbers higher. 

Survivability

It is nice that Ruler Skadi has a decent sized HP pool and has Ruler classing to halve most types of incoming damage. However, she has no hard damage mitigations, and in fact no way to lower incoming damage at all. The only way she can avoid taking a Noble Phantasm to the face is to use her own Noble Phantasm which comes with the ability to decrease an enemy’s charge by 1. This is only a 1-turn delay, however.

High Investment Requirements

If a Master does not have a team with many of the top supports, a Ruler Skadi is only slightly better than the original Skadi. She can still enable looping with a Kaleidoscope on the AoE Quick Servant and a support Ruler Skadi, but this damage is typically much lower than the other metas. One needs to have either a Caster Skadi or an Oberon to unlock her higher potentials. 

Lack of Sustained Crit Absorb

Ruler Skadi’s third skill only gives a boost to Buster Crit absorb for a single turn. If looking to “attack with the B cards” as a strategy, this could result in several critical misses.

As there are three unique ways to use Ruler Skadi, her Craft Essence Recommendations are highly varied. If looking to use her as a Quick loop support, Masters would be best served using Bond Bonus CEs and event bonus CEs to boost overall progress in the game. If looking to use her as a Buster Crit support, either her Max Bond CE or a Critical Star Regen CE works best. If wanting to use her as a damaging Servant, either a Noble Phantasm Damage Up CE or a Mixed Damage / Starting Noble Phantasm Gauge CE works best.

• Chaldea Lunchtime / Chaldea Teatime / Fist of Hail: In most farming situations, Masters want to boost bond or event drops. As Ruler Skadi is often a support, she will serve best boosting these. Note: Fist of Hail is listed as a sample event drop boost CE.
• The Silent Tears of Enchromia: Ruler Skadi’s max bond CE is actually quite nice when a Master wishes to use her to boost Buster Criticals, as it permanently boosts Buster Critical damage by 30% when she’s on the field. 
• A Fragment of 2030 / King of Heaven: Ruler Skadi can passively generate 15 Stars per turn, but as Buster focused Servants tend to have lower star weight, getting another 8-10 per turn could make that much more of a difference. 
• The Black Grail: If using Skadi as a damaging Servant with both a support Ruler Skadi, a Caster Skadi, and either a Nero Bride or Oberon, she can use a Black Grail to maximize her damage. 
• Traces of Christmases Past / Holy Night Supper / Golden Sumo: Boulder Tournament / Kaleidoscope / Winter Crystal / The Imaginary Element / Dragon’s Meridian: If a Master is only looping with 2 Ruler Skadis and a Caster Skadi, refund will be tight. She can manage to loop with a Traces of Christmas, but some of the other standard Mixed CEs would only result in 2 NP fires in 3 turns instead of 3. Kaleidoscope can mostly ignore those requirements by giving her one NP for free.