Brand of Cthugha is good fight spell for mystics, and great alternative of Shrivelling. In my opinion, it's fine to get BoC only if your role is flexible, or BoC + Shrivelling if your role is fighter.

Then, what's difference between Shrivelling and Brand of Cthugha?

• Net-damage is similar in most case: Shrivelling(5) has 12 net-damage as maximum, and BoC(4) has 9 net-damage. However, you can control charge for BoC; if you attack 2-health enemies or 4-health enemies, BoC is better. In most case, net-damage is almost same except boss raid case.
• Backfire effect is controllable: BoC has terrible backfire effect, which make you lose 2 action which cannot be prevented by Deny Existence. However, you can control backfire unlike Shrivelling. For standard difficulty, chaos bag contains lots of -1 and -2, and single -3, -4, or -5. To avoid backfire effect, you just boost your skill value as "failure only if " or 4 more which only 1 token generates backfire. If you perform attack as last action, you don't need to consider backfire since you have no action to lose.
• Failure penalty is really small: When you fail a skill test, you have no backfire effect of spell and no charge is spent. Moreover, it's burdenless to attack the enemy engaged with another investigator unlike Shrivelling because they take only 1 damage(or zero? it's arguable) even if you fail the attack test.
• No synergy with charge-based card, so durability is not good: Since BoC(4) spend lots of charges, it's bad to use charge-based combo such as Book of Shadows, Recharge, Twila Katherine Price, or True Magick. Additionally, it's not good to choose BoC as the target of Knowledge is Power, since you should spend charge even if you play KiP. Thus, if you want to use BoC continual, you should find another method like Spirit-Speaker, Prescient or cycling your deck.

I think this compares somewhat poorly to Leather Coat coat and I'd rather take that if I can. Waiting for 3+ spells over 3+ turns to just breakeven makes this a hard sell. Sometimes you draw it late and you arent playing any more spells. Even early on, it feels slow to play this, gather more resources and play your main spells.

But not every can take leather coat. Robes of endless night does however compare favorably to the neutral Trench Coat and decently to Heavy Furs. Only Sefina has enough agility to even think about evading but she is even more heavy on spells.

Heavy furs might be useful in Diana Stanley and maybe Jim Culver but for the most part, the economy is better than an extra reroll because mystics usually do want the health soak for themselves. The reroll on symbols is occasionally useful to avoid the downsides of your spells but mystics have other avenues to avoid that.

It's generally obvious when you'll take this, a mystic with low (5) health and lots of spells (maybe around 10 spells). With around 10 spells, you should be able to play 1 every 2 turns and make back your cost after 6 turns (about 1/3 of the scenario).

The wording of this card seems to respect the play style recommended in the guide book about staying in-character and not saying what cards you have in your hand to play/commit. Because the text makes you reveal what you would like to offer first, then "may" and "if they do" decide whether anyone actually want it or not. (You can probably say you have "good stuff" and call for a group-up, for immersion.) Otherwise, you would not play this card in the first place if it would ended up that no one choosing to play...

If you are playing "hard mode" that an entire table is staying in-character, it is possible that this card's net result turns into a few giggles at a cost of 1 action. (giggles are worth it at only 1 XP!)

There is a neat little trick combining this card with Eye of the Djinn to get a based skill test +6 (two copies to get +7) once per term using Eye of the Djinn's ability. The three investigators who can make use of this combo Tony Morgan, "Skids" O'Toole, Leo Anderson will all appreciate it.

-- Update: after checking with Fantasy Flight AHC about the ruling. The combo unfortunately does not work.

This is what Fantasy Flight wrote:

• All of the ability text on Eye of the Djinn would resolve before drawing skill tokens for the test. Eye of the Djinn will set up a “lasting effect” (base skill of 5 for the test) and two “delayed effects” (if you draw a Bless or Curse token, do X) that can still affect the game, but the card itself has resolved.
• Consequently, Reliable will only grant you +1 to your skills while the asset it’s attached to is resolving a triggered ability. The timing window for this modification ends when the asset it’s attached to is finished resolving—in this case, Eye of the Djinn will have finished resolving once you begin drawing tokens for the skill test, and you would revert back to having a base skill value of 5 until the end of the test.
• (This is different than if Reliable were attached to an asset with an action triggered ability, such as a weapon with a Fight action.)

Question for all our rules lawyers out there:

Does the latest Taboo stack with scope?

“This attack may target a non-Elite enemy up to one location away from its standard range, ignoring the aloof and retaliate keywords.” Taboo basically reads "Standard Range +1 Location away".

Scope as a reaction allows a Firearm to target adjacent location. Would that be considered the new standard range then and allow the Springfield plus Scope to target two locations away? WHich would be awesome and very unique

If not it would mean, you could gain basically the same effect but better with sticking the newly tabood scope to your shiny 4 or 5-xp-firearm. you would only ever take the springfield to save on some xp as the BAR or the Lightning Gun are still better in their own right. You could always take a higher value two-handed firearm and stick a scope on it for whatever xp your weapon costs +3xp for the scope. And lets face it, which guardian skims on the xp concerning the primary weapon?

Don't get me wrong. This new version stands head and shoulders above the old one. But XP should not be a concern for the guardians primary. So I would always take the best or most flexible base weapon and stick scope to it, if wanted to target adjacent. But targeting two locations away by adding a scope on top? That would really allow some unique camper playstyle in MP where you guard your team by sitting at a center location and picking everything off from a distance.