In D&D, once the characters in a party get too many levels, and start accumulating magical items, it can be difficult for a DM to give them a worthy challenge. While the DM can use the usual enemies for a high-level party, like dragons or beholders, it is better to give the players a challenge they were not expecting. This keeps the game from getting stale and repetitive; and gives the players memories of their characters’ adventures that will stand out from the others. A couple of these enemies/monsters have yet to be introduced to 5th edition, but even a beginning DM should have no problem converting them to the new rules.
10 Invisible Thieves
(Via: Wizards of the Coast)The prospect of fighting a group of high-level thieves that all have the ability to turn invisible multiple times during an encounter is not something most parties are prepared to deal with. This is easy to set up for a DM; the party enters a new city, and the local thieves guild take note of the powerful magical items they are carrying. The encounter begins with every player being the victim of a sneak attack, and don’t be afraid to give the thieves some magical weapons – like daggers of wounding. To make it more of a challenge, give some of the thieves levels in spell-casting classes.
(Via: Wizards of the Coast)The Slaadi (or Slaad) are other planar beings native to Limbo who resemble giant humanoid shaped frog creatures. There are several types of Slaad, differentiated by color. A group of blue Slaad, with maybe a green Slaad leading them, will provide a good challenge for high-level characters. The blue Slaad have a good armor class, a ton of hit points, magic resistance, and can poison enemies. The poison will turn the victim into a Slaad if not cured. To make them more of a challenge, have the party fight them in Limbo – Slaad are immune to the plane’s adverse effects.
(Via: Wizards of the Coast)Chasme resemble giant flies, but are in fact powerful demons. If a party hasn’t encountered them before, they might think they are simply giant insects; which will likely cause the players to underestimate the danger Chasme pose. They have a lot of hit points, a decent armor class, magic resistance, and can deliver extremely damaging attacks. Chasme can deal almost 70 points of damage per turn, and some of this damage reduces the target’s maximum hit point total. Also, like most demons, Chasme can summon more demons into the fight. Lastly, they produce a droning sound that can cause those hearing it to fall unconscious.
(Via: Wizards of the Coast)Deepspawn are unusual creatures. They are huge fleshy orbs with multiple eyes placed around its body. Protruding from the body are two types of tentacles. One type are standard tentacles; which can be used to wield weapons (which can of course be magical for added challenge). The other type of tentacles end with a toothed maw, and can deliver biting attacks. Deepsawn have a respectable armor class, and enough hit points that it will take a long time to get them to 0. The worst part of fighting them is that they have the ability to replicate any creature they have consumed (which can include most monsters due to the size of the Deepspawn).
(Via: Wizards of the Coast)Sending the players into an underwater setting is already taking them out of their element (literally), but having them fight a morkoth might be one of the toughest fights they have had up to that point. Morkoth are large monsters that resemble a cross between a frog, fish, and octopus. They are incredibly intelligent and malevolent creatures with an impressive amount of spells at their disposal. They have a high armor class and hit point total; they are also capable of dealing substantial physical damage if they are unable to cast spells. Morkoth also have a natural defense against spells that actually allow them to reflect offensive spells to a target of their choice.
(Via: Wizards of the Coast)Archomentals are very powerful denizens of the Inner Planes. They are about as close a creature can be to being a god –without actually being a god. There is one Archomental for every element. Some of the better known are; Imix is the all-consuming fire, Yan-C-Bin is the prince of evil air creatures ,and Cryonax is the prince of evil ice creatures. Each of the Archomentals have their own special abilities and defenses, and each is usually accompanied by elementals of the same element type as the Archomental. These are not an easy fight, no matter how powerful the party has become.
4 Clockwork Horrors
(Via: Wizards of the Coast)These nasty spider-like creations are basically the Daleks of D&D. They are intelligent, powerful, and singularly driven toward universal domination. There are several types of these horrors, each named after the metal they are composed of; this allows the DM to balance the CR for any party. The gold and platinum horrors, in numbers, can provide a challenging encounter for even high level characters. The entire race of clockwork horrors is led by the Adamantite Horror, which can be the memorable final boss of an epic adventure to rid the party’s home world of these creatures.
(Via: Wizards of the Coast)Modrons are the native creatures of Nirvana (also called Mechanus). The DM can use these in much the same way as the clockwork horrors. The lesser (or base) modrons are simple creatures that resemble simple shapes, like cubes or spheres, that have come to life. The ruling class of modrons have more complex shapes, and can provide a challenging fight for high-level characters. In addition to more complex shapes, the ruling class modrons also possess powerful spell-casting abilities to go along with their high armor class and hit point total. Many of the more powerful modrons also have psionic abilities in addition to their spell-casting abilities.
2 Greater Wil-O’-Wisps
(Via: Wizards of the Coast)The standard will-o’-wisps are fairly challenging foes, but the “greater” variant are outright deadly. They have an extremely high armor class, enough hit points to last for many turns, resistance to most forms of damage, and several innate magical abilities. The most notable of these abilities is the ability to become invisible, and their ability to consume the life of characters reduced to 0 hit points or less – which heals them. A DM can make this encounter even more challenging by including monsters that lower the party’s attack bonuses. Doing this can make the greater will-o’-wisp nearly impossible to hit with physical attacks.
1 Make The Party Fight Among Themselves
(Via: Wizards of the Coast)Imagine an encounter with a village of orcs; a village from which bands of orc warriors have been attacking nearby farms. In this village are orc women and children. If the party is composed of a mix of alignments, this could become a very delicate situation to navigate for the players. The good aligned characters in the party are not going to be able to kill the orc women and children, and should not be allowed to stand by if the less than good party members decide to attack them. This moral dilemma can cause a lot of strife within a party, and make what should be a simple encounter much more complex and challenging.