So I've just Lorded Black Cat and i have A LOT of room to grow with her BUT, after playing 10+ hours of Doom match and 10+ hours on comp, here is a rough idea of which abilities to buy before engaging in 1v1's with an enemy.
Hypno-Fish: Great at securing the kill by removing enemy escapability. Most of these are self explanatory. It's always so satisfying to pop a fish right before venom swings out. This messes with flyers a lot. Hypno-Fish is not always guaranteed value, especially if the enemy is not low health, but it can annoy enemies even if not lethal. The other heroes I have here have jumps/dashes/etc that can get ruined and help secure an elim. I can't recall if hypnofish is that useful against Jeff or Whitefox.
Chernobog's Crystal: I admit I usually forget about this one, but I believe it can remove Luna's Freeze/Peni's Web Stun/Mantis Sleep/Widow's Kick Stun, right? Definitely underutilized by me.
Chernobog's Crystal (FOR ULTS): I don't have Ult's factored in because I tailored this list for neutral play. However, some Ult Cleanses that come to mind are Strange's Ult, Thing's Ult, Angela's Ult, Bucky's Ult, etc.
Unsure: For these heroes I don't see a clear advantage of using Hypno-Fish or Chernobog's Crystal so I would default to having a Helm of Hades since it's the most versatile ability. Correct me if I'm wrong with specifically Blade, Loki, or Cloak, but Hynofish isn't that helpful against them right?
I AM OPEN AND ASKING for input and your experiences best utilizing the Gilded Deal items, because I can tell there's so much I have left to master with on her. Mind you i am a Diamond I-II player on average at the moment.
EDIT: Would move Dr. Strange down to "Unsure" because I am not factoring his Ult into this chart.