The reason I want to do this is because my DM is being mean to a few of the party members for "how basic" their characters are, and he has also TPKd us several times. So using polymorph, I want to walk into the big bad evil guy’s castle, and kill 'em.

(My party is level 8)

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    \$\begingroup\$ There's some subjectivity to this question that could be cleared up by including details on your BBEG as far as the mechanical aspect goes. Is the BBEG a spellcaster? Melee? Sneaky? These things matter when you're trying to pick the best form to take. \$\endgroup\$ Nov 5, 2022 at 20:15

3 Answers 3


T-Rex. But to solve your problem, you and the DM should talk

The classical high end beast for polymorph is the Tyrannosaurus Rex, as it can freely move around on land, has a lot of hp, and a nasty bite. Conveniently, it also is CR8.

Alternatively, especially if you need something with more intelligence that can carry out a simple plan, you can use the CR7 Giant Ape.

However, don't expect that this will allow you to stomp over the villain easily. A party of 8th level should be stronger than a T-Rex, because a CR8 creature is just one of several level-adequate encounters they can expect to successfully defeat each day. So if the villain is a challenge for your party, they should be able to put down a T-Rex, especially in their castle with all their minions and supporting fortifications and siege weapons.

Even more fundamentally, this does not look like an issue you will solve in-game. Your DM has unlimited leverage to out-do whatever you come up with. To me it sounds that there are issues with how they run the game, killing the entire group several times over. Unless that is the game you signed up for — and it does not sound like it — you need to talk with them and make them aware that how they treat the players and run the game is not enjoyable to you. In the end, the DM does not have the ultimate power. The players can always opt out of the game and find another DM, if you cannot work out some solution that works for both sides. That solution can only be found by talking it over out of the game, not by polymorphing someone into a T-Rex or any other in-game means.

  • \$\begingroup\$ I mentioned it in a comment on the other answer, but this answer seems to miss a significant drawback of the T-Rex: it cannot attack the same target twice in a turn. \$\endgroup\$ Nov 6, 2022 at 0:10
  • \$\begingroup\$ @ThomasMarkov Note the T-Rex is the only good land based CR8 option and the OP is asking for a CR8 monster. The Ape is good too, but is not a CR8, its a CR7. \$\endgroup\$ Nov 6, 2022 at 0:15
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    \$\begingroup\$ Okay, but I’m pretty sure OP would want to know if there was a CR 7 option that might be better than the CR 8 option, even though they asked for a CR 8 option. Also I’ve had a lot success using the Sperm Whale. Just ask NautArch what happened last time I became a Sperm Whale. \$\endgroup\$ Nov 6, 2022 at 0:17
  • \$\begingroup\$ @ThomasMarkov Yes, and I have the Ape in there too. I think what creature can deal the most damage against a single target is not the core of the question. Its a side aspect we happen to take interest in. Whale is also great in the right circumstances, but as it cannot move, very situation-dependent. \$\endgroup\$ Nov 6, 2022 at 0:19
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    \$\begingroup\$ @GroodytheHobgoblin Honing in on the single-target damage aspect is relevant because the stated goal is to "kill the BBEG" and while there will almost certainly be more than one enemy present, the ability to stack damage onto a single target and eliminate it while surviving becomes the most important combination of factors to the equation -> It's also why I value the climb speed over 10 extra feet of land speed and the 21 extra HP over the +1 AC -> AC12 and 13 are both going to get hit often enough at that CR that the extra HP for the form is superior, IMO. \$\endgroup\$ Nov 6, 2022 at 1:59

Giant Ape

The primary limitation of polymorph is that you can only take beast shapes. With that said, in this range there are two shapes that have similar AC and hit point totals, with the variation being mostly tactical in nature- but that's not something you should overlook.

The T-Rex has 21 less HP than the giant ape, but moves 10 feet faster on the ground -> It has no climb speed, however, and it can't focus its multi-attack on a single target.

The giant ape has 1 lower AC (12), but it's also a biped and you could hypothetically look for a way to get larger armor to wear on the form, including paying for what would normally count as "barding." This means your giant ape with two swings of +9 can focus 40+ damage on a single target with 18 AC if you're willing to drop a chunk of gold or a valuable item for it- and it also has a +9 to athletics for actual grapple lockdowns (athletics vs. athletics/acrobatics as opposed to having to hit AC that might conceivably reach 25+) with a 10 foot reach - one that is as hard or harder to escape than the T-rex's 60% of the time. As the final cherry on top, the giant ape can actually competently grapple creatures above medium size, all the way up to gargantuan, so an enlarge spell on the BBEG won't nullify half of your main attack.

It's also got a climb speed and a ranged attack worth 30 average damage. In most situations where I'd consider a T-Rex, I'd consider the giant ape superior.

Edit: In fairness, you could pull the barding trick with the T-Rex, but the giant ape can also hold a shield...

But I do agree with Groody. The real problem here seems to be an atmosphere of condescension from DM to Party, and that sounds like dissonance between game expectations. A conversation might fix this, or your group might be better off looking for a different DM that accounts for the dynamic of different player skill level within their game rather than mocking them for a lack that can be learned.

  • \$\begingroup\$ +1 It also (and I think that is worth a lot) has a higher Intelligence than T-Rex. I thought about citing it too, but I typically see T-Rex. I'll add it to my answer as an alternative. Note that it cannot do anything that uses hands if from polymorph, so I think a shield would not work. \$\endgroup\$ Nov 5, 2022 at 23:38
  • \$\begingroup\$ I've not done the damage calc, but the T-Rex has a raw damage output of 53 vs Ape 44, plus a +1 higher to hit to make it connect, and gets to grapple with retrained without an action with the bite, imposing another +4/+5 from advantage to hit the next round and making it hard for the victim to hit back. I think it would deal more damage overall, and if it has bite grappled someone the expected damage from the bite alone will rival the ape's overall expected damage due to better to hit with +10 at advantage. \$\endgroup\$ Nov 5, 2022 at 23:52
  • \$\begingroup\$ @GroodytheHobgoblin The TRex’s problem is it can’t focus fire. \$\endgroup\$ Nov 5, 2022 at 23:54
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    \$\begingroup\$ @GroodytheHobgoblin Emphasis mine: “Multiattack. The tyrannosaurus makes two attacks: one with its bite and one with its tail. It can't make both attacks against the same target. \$\endgroup\$ Nov 6, 2022 at 0:04

The Huge Giant Crab from White Plume Mountain

For comparison:

Giant Ape: AC 12, hp 157, attack bonus +9, damage 44
T-Rex: AC 13, hp 136, attack bonus +10, damage 53, auto-grapple Medium with Restrained, must attack two targets
Huge Giant Crab: AC 15, hp 161, attack bonus +9, damage 54, auto-grapple anyone

I agree with the other answerers that this will not solve your problem with your DM. You need to make sure your DM knows that it's not fun for you when the battles are this difficult.

I also want to note that using polymorph on yourself is usually a bad plan, because you will lose concentration quickly when hit. You lose the benefit of your feats (such as War Caster) when polymorphed.

  • \$\begingroup\$ White Plume Mtn. is in Tales from the Yawning Portal, is that right? \$\endgroup\$
    – nitsua60
    Nov 6, 2022 at 17:17
  • \$\begingroup\$ That sounds right. \$\endgroup\$
    – Dan B
    Nov 6, 2022 at 17:25
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    \$\begingroup\$ Good find. Maybe depends on the GM if they see it as a unique monster, but the stats are arguably the best. Especially the high hp and AC are nice. The restrained aspect adds a bit to damage for T-Rex (I think about 6-7 pts expected) so it still has the highest damage output, at least vs Medium. \$\endgroup\$ Nov 6, 2022 at 22:00
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    \$\begingroup\$ @nitsua60 You can also find the Huge Giant Crab in Storm Lord's Wrath as V2Blast's answer to this question explains. \$\endgroup\$
    – Kirt
    Nov 6, 2022 at 23:58
  • \$\begingroup\$ However, the real limiting feature of the huge giant crab is its Intelligence of 1, even worse than a T. rex. Good luck finding your way through the castle to reach the BBEG. \$\endgroup\$
    – Kirt
    Nov 7, 2022 at 0:00

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