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)
Amazing how the loophole has not yet been closed.
All it takes is for the rules to state that if a second copy of the same source is attempted then the original is destroyed (perhaps with a DC check against the original copy's caster + some bonus, to make it particularly hard to dispel in such a way).
I see it as there are a load of ways to break the game. These are just a few:
1. Cast it on yourself and have your clone cast it on you, creating another clone that casts simulacrum on you. Repeat until you eventually create thousands of simulacrum. Storm the den of the Tarrasque and be a hero.
2. Convince your DM that your clones should have a challenge rating. If they agree, and you are feeling rather evil, slaughter all of your simulacrum for XP. This will probably end in horrified stares and the crying of clones.
That is such a cool idea for an NPC background
This spell would amazing if used as part of a campaign. Imagine a villain using this to impersonate a party's ally or to distract the party in another corner of the world to buy time. Personally, I think it would be interesting to see the Big Bad actually be the simulacrum of an archmage who wanted to retire without anyone knowing or as the plot of a villain to use a modified form to cause havoc using a sealed deity as the target.
Problems with the simulacrum - wish combination:
the simulacrum has no equipment, so no spellbook. Also it can not learn (new spells).
This is not a problem, if you create a simulacrum of the barbarian or sorcerer, but it limits the effectiveness of casting a simulacrum chain on yourself.
In the adventure league FAQ it says:
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.
If one of the simulacra dies, all simulacra under him will "gain independence" and will not have to obey your commands anymore. This quickly backfires, as you have just gained a near all powerful rival, who wants to be the true wizard.
I would allow people to create an infinite simulacrum chain, and then have this happen. They loose control over a large part of their simulacrums, and the players then have to clean up this mess.
This makes for an interesting boss fight, the player will be more careful about this tactic, and it provides an explanation, why other more powerful beings haven't already used this strategy to take over the world.
Couldn't you create a simulacrum and make it cast wish to create a ruby worth 3000 gp. Then create another one with the new ruby and make it wish for a valuable item. If wish backfires and your copy can't cast it any more, you (the original caster) are still able to use wish and you can get infinite money by repeating this process of making your simulacrum wish for items more valuable than the costs for creating a simulacrum.
You can have the wish simulacrum use that for 10 rubies or diamonds or whatever without any risk of losing wish yourself. But if you want multiple simulacrums (simulacri?) of yourself the only way is to have the copy cast it again after you have a long rest and full slots. You can then take the madness further and cast True Polymorph on your sims to make them adult silver dragons that can shape change back into a humanoid form. They make great bodyguards and house keepers and are completely loyal to you as they have the personality of the sim.
Tarrasque isn’t a beast or humanoid. So you can’t copy it anyway.
Everyone who's talking about mimicing themselves is forgetting, you can have your simulacrum cast it on the player, meaning there is no hitpoint decrease from simulacrum to simulacrum. Meaning you could have an infinite simulacrum army that all have half your level. If you have a swole wizard, your simulacrum could be extremely beefy
Can a simulacrum regain class features like sorcery points or channel divinity?
It doesn't say that it can't.
TARRASQUES ARE TITANS / MONSTROSITY NOT BEAST OR HUMANOID.
can a casting of simulacrum duplicate ongoing spell effects already on the target of the spell. E.g. if I created a simulacrum using wish of a fighter that was already hasted, would the simulacrum then be hasted as well? I would also assume that it would be different with concentration and non-concentration spells. So with something like longstrider, that lasts for while without requiring concentration, would a simulacrum created also have the longstrider effect?
RAW it can, however RAI it can't. There are a few tweets saying that they aren't intended to be able to recharge anything, however given that it is RAI, it is up to your DM i guess
Sadly that is a monstrosity not a beast or a humanoid
You couldn't make a Tarrasque, Beast or Humanoid only I'm afraid
If there was also one in range. If a Tarrasque is close enough to be touched then I don’t think I have 12 hours to make a copy of it.
Unfortunately (or maybe fortunately) the simulacrum copying simulacrum doesn't work as the simulacrum are constructs and not humanoids or beasts which is a requirement for the target of the spell