D&D 5E Amulet of the Planes - can one intentionally fail the DC 15 Int check?

[Blue]

You kids probably don't remember it, but there was a time where cyclical initiative wasn't even invented yet, and back then we all rolled initiative every round...

Now get off my lawn

I know, I know, I started with Red Box Basic, not blue book or Chainmail. Don't have to rub it in.

 

[Li Shenron]

My players encountered Juiblex and the Wizard asked to intentionally fail the DC 15 Intelligence check in order to teleport the demon lord, and himself, somewhere other than where they were. In the flow of the game, I wasn't able to quickly locate a rule on intentionally failing magic item stat checks. I ruled it was ok and the Wizard and Juiblex ended up in the Astral Plane. Next round the Wizard won initiative and Plane Shifted back. Demon-be-gone!

Can someone point me to RAW regarding intentionally failing DCs?

"While wearing this amulet (check), you can use an action (check) to name a location that you are familiar with on another plane of existence (check-Astral Plane was the target). Then make a DC 15 Intelligence check. On a successful check, you cast the plane shift spell. On a failure, you and each creature and object within 15 feet of you travel to a random destination. Roll a d100. On a 1-60, you travel to a random location on the plane you named. On a 61-100, you travel to a randomly determined plane of existence."

I think your ruling was ok, but probably the Amulet of the Planes is worded poorly... to me it seems its RAI is to allow you to cast Plane Shift but with a chance of failure. Instead, it is worded in a way that you don't actually cast Plane Shift if you fail the check, but get a separate effect straight away, which is supposed to be a penalty. IMHO those who wrote this description failed to remember that Plane Shift has its own offensive use (which grants a saving throw), and not just the beneficial use, and so the RAW gives you a fair penalty for trying using the amulet in a beneficial way, but totally fails at giving a penalty for using it in an offensive way.

Personally I would have suggested the Wizard to try succeed the Int check and cast Plane Shift offensively to teleport only Juiblex away. And on a failed check, I would have still given Juiblex at least a ST to avoid being teleported. I just don't think that a Wizard's failure should result in her target's loss.

 

[CapnZapp]

I think the best solution is to allow the player to get away with his smart play.

That one time.

By allowing the player the glory of his item abuse it should be easy to persuade him to agree to a rewrite that fixes the loophole, much like what we seem to agree on.

 

[Sword of Spirit]

I think the part about everyone within 15' getting transported is intended to be the downside.

Use Amulet
1. You succeed on Int check...
a) Opponent fails Cha save = Opponent banished while you stay where you are
b) Opponent succeeds on Cha save = Nothing happens; you wasted your action
2. You fail Int check...
a) 60% = Everyone in 15' gets sent to random location on target plane
b) 40% = Everyone in 15' gets sent to Jubilex's lair...I mean a random location anywhere in the multiverse (which could be Jubilex's lair in the Abyess, the pure elemental depths of the Elemental Plane of Fire, or the Demi-plane of Fudge)

While I personally love the idea of being sent to random planes, I'm pretty sure most characters in the game world would rather waste a few seconds of time than risk being flayed alive in the Palace of the Undead Chefs.