This is a three inch high bronze statue of a young man with three closed eyes sitting in lotus position, a snake coiled around his neck. Some well-traveled PCs might know that this is a depiction of the Hindu god Shiva. Shiva is the god of death and rebirth, of balance and transformation brought about by destruction. Detect Evil shows nothing evil about the statue (it is a holy relic), but detect magic works and even gives the player a hint about how to use it.
If someone focuses on the statue after it has already been used that day, then those who previously used it lose their effects. Hit points are reduced, spells are dispelled, and where possible the rolled effect is transferred to the new beneficiary. If multiple people meditate on it at the same time, then only the one who mediates the longest receives any benefit or effect. The exception to this is when a Cleric of Shiva is leading the meditation process—then all receive the full benefits of the meditation, but the GM should roll on the effects table separately for each participant.
If a Cleric of any other god blasphemes by meditating on the statue in order to prepare their spells more quickly, they will immediately lose favor with their old god and become a Cleric of Shiva. It's a good idea to prepare a new list of spells focused on destruction and re-creation for this eventuality. Feel free to use some Magic User spells, but remember that Shiva and his clerics stand for Law, not Chaos. It just happens to be the law of Entropy.
Each time the statue is used, the GM should surreptitiously roll a d100 on the table below and play out the effect as makes most sense. The purpose of these effects is to add some of the destructive transformation that Shiva represents to the campaign. While a character might receive an immediate bonus from the use of the statue, it is only by causing the entropy of the world around them to increase to preserve balance.
As a GM, do not give your players reasons to associate these effects with the statue. Each should have a normal cause in-game, even if it means ret-conning, fudging, or changing plans. Does a wound not heal? Then that must have been a magic sword. Are the bees going to attack? Wait until the next encounter check and fudge the roll. Did their house burn down? They won't find out about it until they go back or a hireling seeks them out.
Once an effect is rolled, scratch it out and add something new.
1-74: Nothing happens.
75: The next time the character wants something from an NPC, no matter how well they negotiate or roll the answer is "no".
76: The next time initiative is rolled, increase the hit dice of all the creatures the players are fighting by 1.
77: Before the end of the day it will begin raining. If it is below freezing where the characters are, it will not fall as snow, but rather ice rain.
78: The next time it thunders, lightening will strike the most heavily armored character in the party.
79: The character's closest relative just died.
80: The character's house just caught fire.
81: From the next blow to the head, the character will develop prosopagnosia (inability to recognize faces) for 5 days.
82: The next time the character takes damage, they permanently lose that damage from their total hit points.
83: The character is unable to close their next wound without magical healing.
84: One of the character's hirelings (or close contacts) will sever all ties and never speak to the character again.
85: The next time the character is outside for more than an hour, they will be attacked by a swarm of bees.
86: If the character is a magic user, they mysteriously gain the summon spell the next time they prepare spells en lieu of one of their first level spells. It will continue to take a first level slot until it is used. If the character is not a magic user, then at some point today they are going to step in some poo.
87: The next time the character levels up, they do not gain a new hit die.
88: Alcohol no longer gets the character drunk. It is still a poison, however.
89: The character's hair will permanently turn grey over the next month. Any attempts to dye it will result in it falling out.
90: The character develops stage fright and must save vs. paralysis to speak in the presence of more than 15 people. Public places and fights included. This lasts 6 sessions or until leveling up, whichever is longer.
91: Horses absolutely refuse to be ridden by the character. Donkey's don't mind.
92: With the next blow to the head, the character loses the ability to read for 5 days.
93: The next time the sun sets, it will not rise for another 29 hours.
94: The next time the character attempts a disguise, a childhood friend will recognize them at an inopportune time and attempt friendly discourse.
95: The character will receive a vision of love and aid from a dead love one.
96: The character gains one hit point to their total the next time they accept magical healing.
97: A lost item or pet unexpectedly and happily returns.
98: The next time the character negotiates when selling items, they will receive 25% more than the expected amount. This counts towards XP.
99: The next three days are beautiful weather.
00: The statue is lost and will not be found again.