Xu You and general Cao Ren came up with a strategy to celebrate Lord Denethor's birthday, they asked Gandalf for magical help to occupy Denethor while they prepared the chinese fireworks.
This very evening, at a large scale public picnic. Gandalf stealthy sat next to Old D, reached deep under his robe, recited an incantation and spilled a bucket of water at him which made him DISAPPEAR. Henceforth Denethor was trapped in an alternate dimension and could only appear in our world as a ghost next to running water.
Cao Ren could simply spill water once the fireworks were lit to summon the birthday boy and surprise him.
Which he did on the 5th of Thermidor. Denethor was delighted by the show.

This was revealed to me in a dream while napping alongside this thread. Maybe you can use this information to save 4chan or beat that baseball game.