Oh wow thank you this is a very useful post. Let me try to explain a few things but you have helped a lot.

The reason for the complication is my table LOVES critical fails. They nearly cheer when a 1 comes up.

I did totally space on adding damage to the fire ring and will amend that. It's purpose was to make grappling more fun for my fighter that feels left out by all the cool spells and abilities flying around.

The cloaks second one roll is supposed to be a bad outcome actually. The ability to not be seen by anyone including yourself for several hours would make being a party difficult. But maybe I will change it to making you intangible instead since invisibility could end up being pretty strong. And as this is a bonus to the roll you could still add your prof normally if you roll a 1 here just that you would only get half the benefit of this item.

Merchant I clearly need to get more specific with. It is meant to let them grab simple items without having to turn back to a town. Something that's come up more than once for us. Thanks again to those critical fails lol. That said you should be able to buy anything that is for sale in the nearest town so if you were for some reason willing and able to buy slaves at double price then you could. It lasts as long as the transaction takes and yes you could sell him magic items for a big loss.

And the pendant would be something I'd hope they save for big fights but who knows they might blow it asap. It will not regain charges. And it drains the ability that it last boosted I'll update that

And how did I forget what kind of action they need haha I would have to say bonus action for them all. But good luck talking to the merchant in 6 second increments lol