Simply put, when you use a solo, it doesn’t mean it actually has to appear alone. Sure, the Dungeon Master’s Guide says a solo is “specifically designed to appear as [a single opponent] against a group of PCs at the same level,” but the section goes on to say that they are, “in effect, a group of monsters.”
In other words, a solo might be equivalent to five monsters, but you’re not always going to design an encounter that has five monsters. And the reality is, your solo fight is going to be a whole lot more fun if you design the encounter as such.
Over the weekend, I ran two solo fights, one against a bebilith (Monster Manual 2) and one against a beholder eye tyrant (Monster Manual 1). The characters are level 19, so the monsters were pretty much level-equivalent. The encounters, on the other hand, were not—but more on that later. The encounters shared the following traits.
Huge-sized Monsters: I like using huge minis for solos, especially when I can use minis that Pete Lee designed against his own character. I occasionally use them for elites or standard creatures, but nothing says solo like slapping down an enormous miniature on the table. It also tells the players that this monster is serious business, so it let’s them have more fun because they can use daily powers earlier in the fight. Large solos are okay. In general, I stay away from using solos that are Medium unless the creature undergoes a transformation, getting bigger each time you knock away some of its hit points.
Large Encounter Areas: Even if the characters end up immobilizing or slowing the monster for most of the fight, it helps to have a large encounter area. This is especially important for Huge creatures, since they’re going to have a hard time shifting or moving without provoking opportunity attacks. For that reason, I always make sure the Huge solos I’m running have some mobility options, like teleport speeds or shifting effects that ignore marks or occupied squares. If the solo doesn’t have a power like that, I add one.
Add Complication: This really gets to the heart of the matter. Although a solo is equivalent to five creatures, you should use your XP budget (if you use one at all) to ensure that the solo can have some other creatures, traps, or hazardous terrain. In the bebilith fight, there were interdimensional spiderwebs that started spawning swarms of miniature bebiliths. At the end of each round, I had a player roll a d4 to determine how many swarms showed up. These swarms were minions, but they didn’t make attack rolls. Instead, they just did automatic damage whenever a character started next to them. The complication in the beholder fight was a little more exciting. At the start of the fight, the eye tyrant appeared alongside five other Large beholders. The characters had stumbled upon a place where the border between the room and the Far Realm was weak. Each of these beholders was coalescing as it crossed the barrier into the world. Each beholder began as a minion, but each round, they got stronger. I used a d4 to denote this. If a beholder reached 4, it became a fully realized creature with hit points. Until then, each hit would knock the beholder down one step, and if it hit 0, then the creature was killed. So, of course what happened was the players focused on the big bad beholder, assuming it was the worst threat, when the real threat were the minion beholders (I used the beholder spawn stat block from Monster Manual 3), who could potentially really make the battle hard.
Break the Rules: No what your characters are capable of before jumping into a solo encounter. Then, adjust your solo to handle the worst things they can throw at it. For me, this usually means applying the same trait to just about every solo.
Solo that has multiple turns each round (such as the bebilith):
Solo that has only one turn each round (such as the beholder):
If you’re a player, right now you’re probably saying “That totally not fair!” You’re probably right. But it makes for a hell of a more exciting fight. The only thing about these traits is that I generally won’t apply the +5 solo saving throw bonus against effects if I give it this trait, since that really does make things pretty unfair. I still apply the +5 saving throw bonus to moving the monster into hazard terrain, like pits or walls of fire, though, since those kind of things can really throw a hitch in a solo encounter (interestingly enough, the characters in my game tried to throw the bebilith down a hole, which would have meant fighting it alongside the six beholders).
You can break the rules with solo in other ways. If your solo isn’t doing enough damage or representing enough of a threat, amp up the difficult when it becomes bloodied. Give it an extra turn or an extra attack or two, even if the stat block doesn’t call for it. I identified right away that the bebilith wasn’t going to be a threat going only twice per round with a single standard action, so I gave it an extra turn and I let it use all its actions. It definitely made for a more exciting fight. A fight against solos requires a DM to improvise more than in other fights, because such encounters run the greatest risk of being boring. The battlefield tends to be more static, so you have to find ways to keep the players engaged and on their toes.
Make it a CHALLENGE: In my opinion, a solo fight should never feel like the same difficulty as a standard fight. They should always be harder. I mentioned earlier that although I pick level-equivalent monsters, I don’t craft level-equivalent encounters. The encounters in which I use solos tend to be between 2 and 3 levels above the party level. The bebilith encounter was about 2, and the beholder was 3 or 4. I don’t use XP budgets, so I couldn’t say exactly. Generally, once I’ve picked a solo of about the party’s level, I use the complication or the encounter area to bump the encounter up a few levels. Solo encounters should be some of the most meaningful in the game, and this is one way to do it. (Oh, and if you’re one of my players reading this, and you don’t think the beholder encounter was that hard, look at how many daily attack powers and utility powers you have left and then decide; then remember you just started your adventuring day).
Tier Matters: A solo fight at each tier is a very different experience, not because of the proportion of damage the characters can deal, but because of the number of status effects they can throw around. This fact ties with my point about breaking the rules. Hit points and defenses can scale easily with level, but monsters’ abilities to deal with all the adventurers’ tricks is not as easily scalable. You should recognize that, and find creative ways to overcome it. In addition to the traits I mentioned, you could have the solo appear in stages. You could have all effects on it end when it hits 75%, 50%, and 25% of its hit points. You could add immunities (though I discourage this one). You could make a form of variable resistance that applies toward conditions rather than damage types.
The players ultimately triumphed over the bebilith and the beholders. Only one character died, and technically he was petrified. The fights were exciting up until the end, and despite running two solo encounters in a row, each felt very different. So don’t be afraid to use solos—just realize that not all solos are created equal, and nor should the encounter involving them.