Hey everyone,
Now that the whole Innsmouth Conspiracy (and more) has been released, how about having a new look at our friend Sister Mary?
Please leave your suggestions for her in comment section! What are your successes and disapointments while playing her?
That being said, it seems like there are 3 different Paths to take for her:
The  Path, the  Path, and the  Path.
1) The full  Path
 A] How to boost her ? 
Sister Mary has 4 , being her higher base stat.
On top of that, Sister Mary benefits from a certain amount of cards that bring  to our fellow .
• Bandolier (2) if you are packing a .35 Winchester or 2 Spirit Athame
• Holy Rosary first and Holy Rosary
• Nephthys that is insane for her, test-less damage and capturing all the  tokens
• Police Badge that we most likely won't be using as it competes with Holy Rosary
• Brother Xavier that is a bit expensive and not really used to his full potential here
• David Renfield that is great to set up the game, but we don't have many easy ways to kill him except for Ward of Protection
Once your game is set up, Sister Mary will have around 7 to 8.
 B] What to do with that ? 
Then to leverage that high , we have a certain amount of cards available:
• Radiant Smite is the first one that comes to mind: many damages and cheap. A staple for that Path.
• Of course, all the suite of Spells, preferably horror dealing oriented, Clairvoyance, Shrivelling and why not updating our spell to Rite of Seeking (2). 
• Using Sign Magick thanks to your Bandolier (2), you can also bring Sixth Sense and Wither to save charges when they are not useful.
• Sword Cane always good for Evading.
• Enchant Weapon is insane but is not necessarily the best in this build unless attached to your Spirit Athame for a once-a-turn 2-damage hit.
• Enchanted Armor that makes this build extremely tanky, but if that's what you're looking for, Shield of Faith is a solid contender.
 C] Overall build: 
Even though  Sister Mary will not be as strong as a built-in  such as Jacqueline Fine or Akachi Onyele, thanks to Stick to the Plan, combined with Ever Vigilant and Emergency Cache Sister Mary has the reliability that is comon to  to make this build viable and easy to set up for beginner players.
2) The full  Path
 A] How to turn her 3 into a damage dealing machine? 
• Sister Mary has access to the full  pool. This means that you can equip her with big guns: .35 Winchester, Shotgun or the thematic Holy Spear.
• In order to have a good use of her weapons, she needs to improve her base : For this there are the commonly used Beat Cop (0) and Beat Cop (2) and Grete Wagner. 
• Well Prepared is also mandatory once you have purchased your big gun option.
With Shotgun + Well Prepared + Grete Wagner + Beat Cop + Charisma, you shoot with 10, not even considering the fact that you have high chances of finding a . If you use the Holy Spear instead, you fight with 11 when sealing  tokens.
That is good, but still lower than most guardians.
 B] How does Sister Mary compete with other ? 
Drum rolls: 3 things: her  splash, her high  and her constant generation of  tokens.
• You may be asking why I've mentioned Shotgun over Every Other Big Gun? Now consider having this combo: any of these combos: Bandolier (0) or (2) + Grotesque Statue (2) or Premonition + Favor of the Sun, Favor of the Sun + Recall the Future, Scrying Mirror + Enchant Weapon (after pulling the chaos token with Scrying Mirror, you can decide to use Enchant Weapon or not as they are both activated between Phase 1 and 2 of the Skill Test), and most likely many others...
_You can shoot hard and tutor the number of damages you make based on your needs._
• The Holy Spear on its side requires more  management, for example Hallow to release all the seals tokens of your Holy Spear after 5 boost attacks, to remove 1 doom. The absence of Ammo makes it more reliable.
• Finally the .35 Winchester can be really powerful with Olive McBride, Favor of the Sun, Grotesque Statue and Recall the Future to compensate your low .
 C] Overall build: 
Thanks to Enchant Weapon and/or Holy Spear that you can fuel thanks to your unique  token generation, Sister Mary can be as effective as most guardians when it comes to dealing with enemies, with the bonus of helping your teammates to pass their tests.
The Path in between:
 A] Why should you take an in-between  and  Path? 
There are multiple reasons why a  focussed Sister Mary should still think of improving her  later in the campaign:
• For solo/flex, a high  with Sixth Sense / Clairvoyance improved into Rite of Seeking (2) to still be a good cluever.
• For a better use of your Enchant Weapon which is most likely an overkill anyways.
• For a better encounter prot as well as an increased generation of  tokens thanks to Holy Rosary and "Let me handle this!".
 B] Cards to consider to improve your  
As a second priority, after the purchase of a reliable source of damage as mentioned earlier, you can look at improving your  with cards that have a double use: 
• Bandolier (2) that also allows you to bring you Grotesque Statue (2)/Sword Cane along your main weapon.
• Holy Rosary as explained earlier.
• Rite of Seeking (2) in the late campaign if you want more flexibility.
 C] Overall build: 
Out of the 3 builds here: Shotgun is really fun, .35 Winchester also brings the excitement (or frustration?) of pulling that  or not, and Holy Spear is both deadly and reliable...
Nevertheless, they are all working properly, especially for the Holy Spear that can be taken easily to Hard or even Expert difficulty if you want true horror.
And the obvious big advantage of this build is that you can also investigate when there are no enemies, with Clairvoyance/Rite of Seeking (2) if you're playing multiplayer, and Sixth Sense if you're going solo while also giving you really solid encounter protection against  tests. 
Conclusion:
It first seemed that Sister Mary needed her  to be prioritised over her , giving us another "fake " like Carolyn Fern. But as the cycle was released, the game designers showed us that they had other plans for her. Thanks to some  tricks, juggling with  tokens and manipulating deadly weapons, she is a real damage dealer. That is why she is a well-deserved .
If you're looking at creating a deck for a less common investigator, one that is a bit more elaborated than a full-gun Mark or Leo, then I would highly invite you to look at Sister Mary, the real Dark Horse of Arkham Horror.