You shape an illusory duplicate of one beast or humanoid that is within range for the entire casting time of the spell. The duplicate is a creature, partially real and formed from ice or snow, and it can take actions and otherwise be affected as a normal creature. It appears to be the same as the original, but it has half the creature's hit point maximum and is formed without any equipment. Otherwise, the illusion uses all the statistics of the creature it duplicates, except that it is a construct.
The simulacrum is friendly to you and creatures you designate. It obeys your spoken commands, moving and acting in accordance with your wishes and acting on your turn in combat. The simulacrum lacks the ability to learn or become more powerful, so it never increases its level or other abilities, nor can it regain expended spell slots.
If the simulacrum is damaged, you can repair it in an alchemical laboratory, using rare herbs and minerals worth 100 gp per hit point it regains. The simulacrum lasts until it drops to 0 hit points, at which point it reverts to snow and melts instantly.
If you cast this spell again, any duplicate you created with this spell is instantly destroyed.
* - (snow or ice in quantities sufficient to make a life-size copy of the duplicated creature; some hair, fingernail clippings, or other piece of that creature's body placed inside the snow or ice; and powdered ruby worth 1,500 gp, sprinkled over the duplicate and consumed by the spell)
This^^^
I often lay the deal out for my players - if you can do it, then so can the infinite number of bad guys out there. I would prefer to not run that type of game.
Unfortunately, wizards of the coast released a statement specifically saying that simulacrum cannot cast simulacrum
The Tarrasque is niether beast or humanoid unfortunately.
if i'm lvl 18 and know simulacrum and wish, i can create a simulacrum, make him cast wish and wish money. Then i destroy the simulacrum and do it all again, is that valid?
The way I interpret this spell is that, once cast, and the simulacrum is created, it can never have a 7th level spell slot, if you're using it to duplicate yourself. Since, you have to cast the 7th level slot in order to cast this spell, in which case, the copy of you would exist exactly as it does in that state - with a spent 7th level spell slot. That doesn't stop you can memorizing wish, or using a wish to cast this spell, for example. But the other restriction still applies - in that there can only be one of them.
"You shape an illusory duplicate of one beast or humanoid that is within range for the entire casting time of the spell."
The Tarrasque is monstrosity.
They also released an explicit statement that said that all RAW will either be contained in the officially released rulebooks or Sage Advice. So if someone like Jeremy Crawford tweeted it or someone else, it's not considered RAW unless it's in either of these places.
I have serious issues with this spell from a game balance perspective (as a player and as a DM, even for high tier it's bonkers how unbalanced it is), but it did give me an idea to use as a DM:
Basically, what if the stereotypical wizard NPC that the party befriends is actually a simulacrum of a long-dead wizard who used the simulacrum chain trick to create a bunch of duplicates of themselves a long time ago? Based on what works best for your campaign you can decide how many spell slots the simulacrum has left after they were first created (guaranteed not to have a level 9 slot since it would've been used to make another simulacrum) but even if they have all of their normal slots they would still normally only use cantrips, ritual spells, and magic items in day-to-day life. The limited spell slots, and the fact that they only have half HP and can't heal normally, provide in-world reasons why they don't just solve all the party's problems for them, or why they would need to hire the party to do the adventuring for them in the first place. And they could theoretically be killed off at any point through dispel magic. Ironically, this super broken spell is (in my opinion) one of the best ways to have the wizard NPC without having to worry about them being too powerful.
Also monkey pawing this wish it doesnt have to be a simulacrum you can control. Wish is trouble cuz the concept of a monkey paw exsists.
True, it says humanoid or beast. However, I wanted to let Giants, Liches and Vampires cast it, and other types of intelligent casters, so they can at my table Nobody gets to do the infinite simulacrum thing though.
Just imagine the horror of fighting the Lich, he goes down, and instead of crumbling to dust, it melts into a sludgy pile of ice. Forget the phylactery, now you gotta find the real lich.
Or the Vampire who can, apparently, go about during the day, making the use of a Simulacrum a great way to hide one's nature and get things done while the sun's up. (just don't copy the sunlight hypersensitivity thing)
Interesting plot devices. Not a bad use of a houserule; at least, in special cases. But, like you said, if you allow it to go beyond humanoids or beasts for players, it can get out of control (i.e. the Tarrasque)
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This spell needs to be 9th level. Being able to wish for a new one every single day bogs down the game and doubles the amount of time and power an already-bogged-down-with-spells sorcerer or wizard has in combat.
The thing that I think mitigates this spell being OP is that it "obeys your spoken commands, moving and acting in accordance with your wishes and acting on your turn in combat". I take that to mean that it's not a self-thinking entity and doesn't take action on its own without direction. You could give it some more complex commands for non-combat or pre-combat situations (like a contingency trigger) but its still only going to act within the parameters of those instructions.