Was roped into helping a guy plan a campaign for D&D...

[Tomas Elliot]

... But there is a problem. While my ideas are always sound characterization-wise and plot-wise, and while I am in possession of both the DMG and the Monster Manual (which grants me quite a wide knowledge of the various critters that exist in the game), the problem is that I lack any actual experience DM-ing a battle. Which means that, based solely on my gaming mentality and on the impressions I get from reading the abilities of this or that monster, I might be inclined to consider a certain critter to be an "easy fight", only for it to turn out much harder for the players to beat... Or I might have the reverse issue, overestimating an opponent that is actually quite easy.

Long story short: following a long reasoning, I narrowed down my choice for a Warm-Up Boss to two possible alternatives, an Earth Elemental or a Helmed Horror accompanied by two Animated Armors. I need help from the many people with D&D experience in this forum to help me choose, with the considerations below in mind:

1) Characters in the party start at level 6 (the plan is to get all the way up to 20 eventually, and starting from 1 to get there seemed kinda unrealistic), and are created with a 27 points buy system.

2) For reasons it would be too long to explain right now, our heroes end their first mission chasing down this evil wizard guy, who is a notorious creator of constructs and generally likes employing minions. He is destined to become a recurring villain, so this is why the choice for a boss fight is between Earth Elemental and Helmed Horror: he either throws his strongest construct available at the party, or uses Conjure Elemental to summon the big guy. Either way, he gets away while the party is busy fighting.

3) I was told to use the "Challenge Rating" parameter as reference, but those honestly seem pretty out there: the Helmed Horror resists two thirds of the types of damage an adventuring party (made of characters that were just created, and thus have no magic items) can throw at it, and has no weaknesses, yet its CR is somehow lower than that of the Earth Elemental, despite the fact that the latter, as big and strong as it is, as a MASSIVE Achilles heel which is ridiculously easy to abuse (there is a Sorcerer in the party, and those have 3 Thunder-based spells to choose from at character creation... And I am pretty sure our Sorcerer did pick at least two of them).

Basically, the choice is between a guy with a crapton of HPs and a very strong attack, but weakness to magic in general (Thunder vulnerability side, it is hit normally by almost all other forms of magic, AND it has crappy Dex, so for example everyone's favorite Fireball is a no-brainer against it), and a guy with significantly less HPs and damage output, but resistance to pretty much everything a party without magic items can throw at it. What do I do?

[Raindrop Valkyrie]

Keep in mind.... Challenge Rating changes based on Party Composition. One monster might be impossible for a party but easy as cake for another. CRs are rather general. Typically the more health something has the longer one has to fight it ergo... more CHallenge Rating as it has more time to clobber you into the ground. So it's more accessing what tools a party has and going from there.

Deciding which would be a more suitable challenge for THEIR party is what's important.

[Pyon Pyon Kyuu!~]

Well first and foremost:

http://www.giantitp.com/forums/forumdisplay.php?63-D-amp-D-5e-Next

That forum is all about DND. Make an account and ask on there, people are friendly and knowledgeable. I'm a part of the community and save for a few dumb disucssions that come up every few months, it is a good place.

My answer though is:

A lot of monsters can be destructive to a party depending on composition. The most important thing is to make sure you don't let the fight be trivial (so too little HP or too much, make it seem challenging but not so hard that people get frustrated). You also can't let anyone feel useless. A monster can't be immune to all of the damage types your fighter can deal. Suddenly he is useless and won't be having fun.

Also a good read:

http://theangrygm.com/return-of-the-son-of-the-dd-boss-fight-now-in-5e/

This will give oyu some creativity in changing monsters in your own way.

Have the funs

[Tomas Elliot]

Keep in mind.... Challenge Rating changes based on Party Composition. One monster might be impossible for a party but easy as cake for another. CRs are rather general. Typically the more health something has the longer one has to fight it ergo... more CHallenge Rating as it has more time to clobber you into the ground. So it's more accessing what tools a party has and going from there.

Deciding which would be a more suitable challenge for THEIR party is what's important.

Yes I know the CR should be evaluated in relation to the party... But well, the only thing the DMG says on the matter is, and I quote: "A monster should prove a challenging, but not unreasonably dangerous fight, if it CR is equal to the average level of the party". Now, the average level of a party of freshly created Lv 6 characters is 6. You might have noticed that the monsters I am considering have CR of 5 and 4 respectively, so by following the letter of the DMG, they should be considered "easy fights". But the former resists physical attacks and the latter resists pretty much everything, so yeah, I am inclined to think that a mere numerical approach ("this monster's CR is lower than the party's average level, so they'll be fine") isn't exatly a smart idea.

Well first and foremost:

http://www.giantitp.com/forums/forumdisplay.php?63-D-amp-D-5e-Next

That forum is all about DND. Make an account and ask on there, people are friendly and knowledgeable. I'm a part of the community and save for a few dumb disucssions that come up every few months, it is a good place.

My answer though is:

A lot of monsters can be destructive to a party depending on composition. The most important thing is to make sure you don't let the fight be trivial (so too little HP or too much, make it seem challenging but not so hard that people get frustrated). You also can't let anyone feel useless. A monster can't be immune to all of the damage types your fighter can deal. Suddenly he is useless and won't be having fun.

Also a good read:

http://theangrygm.com/return-of-the-son-of-the-dd-boss-fight-now-in-5e/

This will give oyu some creativity in changing monsters in your own way.

Have the funs

I am not registered to tht website, but I am familiar with it (big fan of OotS yo) and visit it regularly. I have read most of their guides concerning 5e, in fact.

You do make a valid point concerning fun, tho: basically what you are saying is that monsters with resistances should be left for when the party has ways of circumverting them. My only fear is that, well, magical items are going to be featured rather sparingly, so by the time they become available in bulk, the party might have become way too strong for a Helmed Horror... Which in turn would mean missing out on a couple of thematically fitting monsters, that could have made for interesting boss fights. Do you think that lowering the allowed starting level to, say, 4, and toning down the planned difficulty of the whole thing accordingly, could be a solution? To give people more time to get their hands on magical items, I mean.

While waiting for an answer, I will check out this link you posted

[Pyon Pyon Kyuu!~]

OotS is awesome! I'm also a fan.

You can start off with a magic items, let the players choose one uncommon magic item at the start. Any +1 weapon would nullify the immunities anyways. You can also make a way for his resistance to be fun. For example you could do like this:

Make it so he switches his immunities every round with some sort of visual cue. Maybe he could switch weapons as well. When he wields a spear he is immune to bludgeoning and slashing but not piercing. That means the fighters will have to plan accordingly and switch weapons on the go. You could even make the battlefield littered with fallen weapons, making an incredibly cinematic scene where they are picking a spear up from a skeleton's body and then next turn have to drop it and unsheathe their sword. Resistances are fine as long as they don't ruin anyone's fun.

Also it's fine to start at level 6 I believe.

[Tomas Elliot]

OotS is awesome! I'm also a fan.

You can start off with a magic items, let the players choose one uncommon magic item at the start. Any +1 weapon would nullify the immunities anyways. You can also make a way for his resistance to be fun. For example you could do like this:

Make it so he switches his immunities every round with some sort of visual cue. Maybe he could switch weapons as well. When he wields a spear he is immune to bludgeoning and slashing but not piercing. That means the fighters will have to plan accordingly and switch weapons on the go. You could even make the battlefield littered with fallen weapons, making an incredibly cinematic scene where they are picking a spear up from a skeleton's body and then next turn have to drop it and unsheathe their sword. Resistances are fine as long as they don't ruin anyone's fun.

Also it's fine to start at level 6 I believe.

While probably not directly applicable to my situation, these are cool ideas too. And I am finding the article you posted to be interesting, as well. You sure have given me some things to ponder