Welcome to EnWorld! This is the perfect forum to post these, and I'm sure you're about to get a
lot of suggestions. I would not call myself the most amazing GM in the world, but I hope to help here.
- Keeping track of spell effects both from PC's and NPCs (stuff like darkness or entagling roots)
If you use minis and a map, one of the best things you can get are tokens or even just like plain yarn. Someone throws darkness down in an area? But a string around that area. Bam. Darkness zone.
If a target is blinded? Put a token next to their mini to signify this. It could just be different colored skittles, even, just something to show "there is something going on here".
Whether you have minis or not, you're going to want either index cards or something to write this stuff down. I have like a little flipbook notepad that I'll take down the names of enemies and then I can easily jot down next to them things like "Blinded until Saves" or "Staggered 1 Rd".
Whatever you use to write stuff down, just also make a note of the creatures' AC and HP so you can quickly reference this immediately.
Making descisions for the enemies. Alot of the time i have trouble figureing out what the mobs would do.
Honestly, this just comes with experience, but I usually try to think about what kind of creatures the party is fighting, how intelligent they are, and how they would realistically handle danger.
Are the enemies of some intelligence (goblins/kobolds) and just saw someone cast Magic? They're probably going to go after that Spellcaster because that's a terrifying thing to confront. They know that magic is powerful (or at least they know that flames shooting from someone's fingertips is generally a bad thing), and wouldn't want to face this any longer than they realistically have to.
Did the mob just lose a lot of their numbers? They'll probably retreat. Most things do not want to die, and rarely if ever fight to the death. Even an Orc or Hobgoblin would rather retreat (and probably regroup for an ambush) rather than just stay in place where they are savagely beaten and their fellows are killed.
For most intelligent mobs, again, look at the party, and then gauge what you might do as a player were you fighting the PCs. Kobolds and such are not dumb: If they see a Ranger and a Rogue loaded with arrows and throwing weapons, they're going to find cover. If they see someone decked out in heavy armor and carrying a shield, they'll either try and gang up on them and find a way to use the "Help" action to gain Advantage and get around that armor, or they'll just keep trying to stay away from that person or hinder them and some way while they fight the rest of the party.
Even animals like Wolves and such
don't want to die: they will run if badly injured or their fellows are killed. This creates an interesting RP choice for the party, too: pursue, or let them go? This creates engaging situations.
Now, for unintelligent or mindless creatures, like Zombies or like Insects, I wouldn't factor too much into tactics: they're basically going for the closest enemy and are going to try and kill it as quickly as possible.
Keeping the combat going: often when dealing with a number of mobs i feel like all my rolling and actions slow down the action
Roll all your dice at the same time. Seriously. Pair off your d20s with your damage dice (preferably the same colors if you can), and say "Okay, these two goblins attack the Fighter, this Bugbear attacks the Paladin, and the other three goblins attack the Warlock", and then roll all of it at once (just making sure you know which dice are assigned to which enemies).
This way, you can just look at the d20s, quickly see who hit, and then you already have the damage rolled. If anything, you can even just do the "Average Damage" that the monster stats have and there you go, that's an even faster way of doing this.
Also of note: how big are your mobs? 5E combat situations can often be faster, a lot more tactical, and a lot more fun if the PCs are fighting 2 or 3 more powerful creatures than 10 weaker ones. That's
far less dice and stats and such to keep track of.
Casting spells: iv been loth to use spellcasting enemies because I feel like ill have to slow down combat to look up the spells. this is even when i have them written down ahead of time because i just dont have the memry to remember what all the spells do so if an NPC has 5or6 spells i need to read all of them which can take a while
Dump the idea of tons of spells for an NPC. If you're just starting out, one or two spell-like abilities would be far more interesting, fast, and fun than having like 5 spells that you know you're only going to use like 2, maybe.
Think of how simple spells can drastically change the dynamic of combat, and use those.
Misty Step surprised the
hell out of my players once when they fought a group of fey creatures that they didn't know could just suddenly teleport. They thought they were at a safe distance and then BAM, suddenly melee!
Likewise, especially at lower levels,
Sleep is simple, there's no save, and it can be pretty potent.
If you can, there's a few Phone Apps out there that are immediate spell references that you can basically build a "Spells Known" list for casters. Just set it up before hand, and then bam, you have the tools you need for a sudden spellcaster encounter with all the spell descriptions and variables literally a touch away, rather than searching through the books.
But again: start small. Treat these enemies as not full Wizards but just monsters or enemies with 1 or 2 neat abilities that they can do like 3 times per fight. Something defensive and something offensive, but the most engaging are usually things that change the nature of the battle (like
Grease in an area, or
Color Spray against a Spellcaster). Your familiarity with the magic and the system will grow as you become more familiar with all these things, and things will naturally get quicker from there.
So, to reiterate:
1.) Always roll all dice at once. Have your players do this too.
2.) Have some index cards or a notebook or something nearby, with the PCs and Enemies written down, so you can easily track Initiative, AC, HP, and statuses
3.) If your enemies are intelligent, play them like it was you as a player fighting the PCs
4.) Remember that things generally do not want to die and will try to protect themselves above all else
5.) Start small with 1 or 2 spells for your enemies so you can better learn to incorporate these powers, and pick spells that are fun and engaging to use, especially if you know the spells well.
