Hello! 

I need some help with some homebrew mechanics ideas 

1. My players are going to retrieve an item that in held withing a security vault that is a set up as a maze of mirrors with illusory and confusing magic. Like an arcane fun house. How can I make this work mechanically without it being one perception or investigation roll that is pass fail. 

2. What are some cool mechanics for fantasy drugs that may have both a boon and a bane. My players are going to this feast where there will be all kinds of drugs. I don't think they will do any at the time cause they are on a mission. But I have a feeling they might want to take some with them. And I think it would be cool if they had something good and bad so they can decided to take the risk of taking for the potential benefit in the future. 

Thanks! 

For the second one, there was an old module called castle amber (or chateau d’amberville). It has a banquet scene where players can choose to have their characters eat or not eat each course. Then you make a save, if you succeed, you get a small benefit, fail and it’s a small drawback.  Small things, like +\- 3 hit points.

I know the module has been updated, or you can probably find the old version for much cheaper and modify it.

For number one, you can actually generate a really hard maze and give it your players, while making them navigate and be aware that there are challenges.

For number two, you could just do a simple + benefit -negative, for example (something I just created):

Boon of unnatural life: This boon lasts for 8 hours or until you complete a long rest (whichever happens first). For as long as you have the boon, you get advantage on death saving throws. However, whenever you heal hit points through a means other than resting, you only regain half the hit points you normally would.

For #1,  make a skill challenge.  This way both you and the players can narrate it and have it be more cinematic and less mechanical.

For #2, take a glance at the Sorcerer Wild Magic table or the Wand of Wonder and steal a few visual effects from there.   Perhaps on an odd roll it's real, and on an even roll its just in the affected character's mind.

Quote from Xalthu >>

For the second one, there was an old module called castle amber (or chateau d’amberville). It has a banquet scene where players can choose to have their characters eat or not eat each course. Then you make a save, if you succeed, you get a small benefit, fail and it’s a small drawback.  Small things, like +\- 3 hit points.

I know the module has been updated, or you can probably find the old version for much cheaper and modify it.

 
Be careful with that one, some of those drawbacks weren’t so “small.” If I recall some of them were instant death.

I loved both Chateau D’Amberville and the sequel The Mark of Amber, those are two of my favorite modules ever of all time ever. And either one could work as a beautiful template for a wacky, high security, arcane fun house vault. They were both literal “funhouse adventures,” and with a little rejiggering either one could be retrofitted to act as what you need. (The sequel was a lot less deadly however since it was written for 2e instead of 1e.)