what are your plans considering usage of multiple accounts by a single player (i do not mean account sharing, where one account is used by more than one player - how to handle this would be another question: but ofc also a small group of persons can control much more accounts and making it even harder to find/analze)?
from what i have observed and what is written here in this forum and sometimes also in the ingame chat multiple accounts are fact.
atm you tolerate it. idk if you already analyze player behaviors (on/off times, play style, hero usage, raid usage, item usage, behavior in wars, … even the ways people use the forge is a fingerprint) to find correlations by use of modern data techniques in background and take actions like e.g. automatic reduction of (unique) item drop rates or personalized perks propabilities.
if you dont know how to analyze big data, imho find someone who can or do your own research on that and maybe also get some patents.
if you already know how to automatic generate indicators which accounts are played by one (or top rated even a group of persons) you could consider the following:
make it leagal - sounds wired but let me explain: if you cant avoid it you have to deal with it and maybe just tolerating or punishing it is not the best way.
so why not do the following: like you can connect your accounts to other players for titan points, why not do the same for multi-accounts: player can link to show hey: i am also using this and this account, but he has to decide which is his main account (and a sub account can not connect further - that would be crazy). this information is made visible in the player info together with a % of the fraction times this accounts are used. (maybe for officers in alliances the activity of sub-accounts are shown when they are online)
ofc this is not enough - but if your system detects a correlations it can first tell the player “hey, we believe you are not playing after our rules. change it” so this persons can react. and after several instances and maybe also manual checking you turn on such connection by yourself so also other player get an idea of what you think is happening and give the alli leaders something so they can decide what to do.
btw: connections to a sub-account with >180 days of inactivity (those accounts are deleted by your system if i get you right from the terms of licence) are canceled automatically ofc.
maybe you can also do this for alliances: every mayor alliance can have sub-allies (bc this also is a fact) - some do it open minded, but some also hidden.
what do you think about something like that? is this all just a minor problem or where are potential weaknesses/exploits of such a system? please think about things like that within your group and discuss it. thx 4 reading, maybe i also overreact have paranoia should not spend a thought on this - but maybe other players feel the same (idk if they use this forum)
P.S. not every multi-account is evil or done for negative purposes, i am sure some have also a positive aspect and good intentions. it would just be nice to know who is who and from what i have found in the new forum it maybe is something that concerns more people: https://forums.flaregames.com/t/multiple-accounts/13309