Just curious, did some looking around and I found the $15 TripelTriHard bot, but saw comments that it isn't very well polished and hasn't received updates in awhile. Wasn't really wanting to spend $15 on something like that.
Having 3 star deck, It took me 200~ hours of botting indolent imperial to get Fenrir. So, if you want to pay $15 and spend 200~ hrs botting, then you can decide if it's worth it or not. Of course you can shorten this time by doing the logs for MGP. The bot works, though running to the NPC has issues, just plant yourself there and go for it a little at the time. It was the most effective method for me, so it was worth it IMO.
I ended up picking it up since there doesn't seem to be any other option. Can I ask what deck you built for farming? I already have about 38 cards unlocked, but none of the main cards that seem to be required for farming it (y'shtola, yda, minfillia, etc). Guess I should really just work on getting it all unlocked first.
Y'shtola, Papalymo & Yda, Minfilia, Thancred, Urianger The bot will also farm the other NPCs decently. Just make an "Auto best" deck and it might be a little lower win rate but I dont remember any single card taking longer than 2 hours.
At the moment it appears TripleTriHard is having trouble working with the latest RB. Just a note for anyone who stumbles across this post.