Adapting Fate/Stay Night into a 5E campaign

Good day, my fellow dice rollers. I am planning to run a campaign set in the Fate universe and would like to ask for some feedback on my ideas. I have been playing DnD for quite a few years but haven’t dealt with much homebrew, so any advice would be welcome.

As of right now, I have 5 people who want to participate in the campaign. The setting is the Fifth Fuyuki Holy Grail War, where 7 Masters compete with each other for the Holy Grail. As you can tell, the numbers do not add up, so I will fill in the missing NPCs. As for how I will split them, I am considering one of the following options:

- Option 1: Each player will create their own Master with an NPC Servant that I will roleplay as the DM. The player will have full control over their Servant during combat, with the exception of me intervening if they try to do something that clearly goes against the Servant's personality.

- Option 2: Players will team up into pairs. In that case, I will ask around in a few of my other groups to see if someone would be interested in joining. This would allow the players to interact more with each other outside of combat and take some load off my shoulders. It would also allow me to fill out four teams with NPCs, which would considerably decrease the time required for each day of the war, as I would not have to DM for five teams but instead a maximum of three.

Now let’s go into the homebrew part which is creating a Master. It would be simple to just set a Level Limit and then let the Master Players create their character using just standard Classes, but would make them too different from the Servants which will have an NPC statblock instead.

Masters

Spellcasting. We will use the regular spelllist from 5E. Instead of limiting them by class, the Masters can learn only spells from the schools they have studied. Each player chooses two schools of magic for their Master and can gain more by spending points. Additionally, a player can choose between Intelligence or Charisma as their spellcasting modifier, Wisdom will be exclusive to Church related characters. Each character gains a total of 10 spells and 4 cantrips with the option to spend points to increase the number known. From here there are two options how I handle spellcasting in this campaign: 

- Option 1. Use the standard spell slot system. This is familiar for players and the safest option. The spellcaster level would be determined by Circuit Quality and Circuit Quantity, which together define the level. For example, a C rank in both would make a character a level 6 spellcaster (more on this below).

- Option 2. Instead of spell slots, we use Mana Points, with each spell costing 1 Mana Point per level. A character would have 3 Mana Points per rank in Circuit Quality and Circuit Quantity. For example, a C/C rank would give a total of 18 Mana Points (with a typical maximum of 30). This allows lower-ranked characters to cast high-level spells. 

Of course a Master does not necessarily have to be well-versed in magecraft, like Ryuunosuke Uryuu. In such a case, the player gains additional points to spend on other stuff.

Ability Scores. I will use the standard point-buy system, with a maximum score of 17 to keep Masters below Servants. Servants will range from E (+1) to A (+5).

Saving Throws. Each player chooses saving throw proficiencies from a class of their choice. 

Proficiencies. Each character chooses 4 skills and 1 tool proficiency, with the option to gain more by spending points. 

Proficiency Bonus. Each character starts with a +2 proficiency bonus and can increase it up to +5 by spending points. 

Traits, Actions, Bonus Actions, and Reactions. This is the part I am least involved in. Each player will design these for their character, and I will assign a cost. They can then choose to include or discard them. There are a few like Average One and Gandr that I have prepared. Also, they are encouraged to take already existing abilities from classes by me giving them a lower cost compared to homebrew (mainly to avoid them coming up with too much and me having to balance that out).

Hit Points. Each character starts with HP equivalent to a level 10 d6 PC and can upgrade the hit die to a d8, d10, or d12 by spending points. 

Circuit Quality and Circuit Quantity. For each, a d6 is rolled to determine rank. Players can spend points to increase their rank to a maximum of A. If a 6 is rolled, the rank becomes EX, allowing the player to assign it a value between 1 and 5. They then gain additional points based on that value (lower value = more points) and choose one special property per EX rank from a list I prepared.

Mystic Codes. Remaining points can be spent on Mystic Codes, essentially equipment and items.

Masters

This part is much simpler. Servants will use NPC stat blocks based on existing information. Ability scores are derived from Parameters, and traits come from Skills. They will also receive additional actions, bonus actions and reactions based on player input, again using a point-buy system. Spellcasting will work like that of the Master. The Servant’s proficiency bonus will depend on the Master’s Circuit Quality.

Noble Phantasms. This is what makes each Servant unique and generally the strongest abilities in the campaign. I plan to use an FGO-style system where Noble Phantasms charge over several turns, with charge time depending on the NPs rank and the Master’s Circuit Quantity. The charges will reset or decrease at the end of each day.

Here the thing I am worried about is that a player controlling a Servant has a lot less influence on the Servant they play then the player who creates a master. While my players are open to playing a Servant, I don’t know if they will really get into playing them when they do not have much freedom when it comes to creating them.

Playing the Campaign

Since this is a PvP campaign, I cannot have everyone sit together and play as in a traditional DnD session. Instead, I will run shorter sessions with each group or player, where they plan their day. After everyone has decided, I will run the actual sessions separately unless there is a chance of groups/players running into each other, in which case I will coordinate schedules.

The campaign takes place in Fuyuki, represented by a map with various locations. During each day cycle, a group chooses locations to explore, with a chance of encountering others, possibly leading to combat. The exact activities at each location I still have to plan.

Each group can also establish a workshop, functioning as a lair.  For example, if Rin is to participate she would have her workshop in the Tohsaka Residence. In her case, the location would be simple to find out but it would be especially strong making it very risky to attack her in it or try to spy on her.

Additional Ideas

With the current system, combat will be dominated by Servants, leaving Masters mostly in support roles. This could make playing a Master feel less impactful. One idea to make them more impactful is to allow them to summon additional Summons during combat, turning fights into more than just 1v1 encounters.

I also considered adding dungeons that Master/Servant pairs can explore to earn Grail Points, which could be used for summons or loot. If I deck out Servants with legendary equipment from the get go the difference between them and Masters would just be too big to have fun. However, I would likely only implement this if players are in pairs.

- - - -

Well, this is what I have at the moment. Thanks for reading this far, I really appreciate it, and if you have any suggestions or opinions they are welcome.