Correct. The ONLY way to get slayer accessories is by using $20 USD to purchase the forge pass. You do also get them for the $50 forge pass but the $30 extra gets you relic crafting parts, gems, and relic upgrades. Most people will tell you though that it isn't worth it though. While the relic crafting ingredence are unique; they're kinda junkie.

You do get a few free by progressing the Forge Pass quests.  Of course they are lower quality and not as numerous. 

I've bought the slayer forgepass 2 or possibly 3 times now, and I still don't have the accoessories to get either Horsey or cheshire cat into 9pc. 😭

Oh damn, here I thought they're forgeable...

Skill issue surely.  Just run 9 Merciless. 

Brings up something I've been meaning to ask:

9pc slayer gives a chance to do additiona damage "by AOE skills"

Does that apply to skills that are single target but conditional AOE? Like Cat's A1, AoE if veiled.

What about's mashalled? Single Target, then also attacks everyone with leech