Do you want your players to claw their way across the sodden fields of battle and confront the enemy general but don’t what just some boring stand up fight? This job calls for environmental effects!
Though seriously environmental effects are great for tuning encounters closer to the challenge a party needs with out needing to drastically change monsters. They have the added benefit of creating atmosphere for the experience and can light up the imagination. Smart players can even use environmental effects to their advantage and create novel solutions to normally deadly encounters.
What is an environmental effect? Generally, any condition to the current scene with a mechanical impact on the characters is an environmental effect. Simple effects like transitioning bright sunny skies into overcast cloud cover count as environmental effects. While the available light is still bright, light sensitive characters would no longer suffer as severe penalties. If the overcast day turns darker rain can fall. Light rain can make stone slick increasing climb DCs. Heavy down pours can even provide concealment after a certain number of feet. Let’s use our battlefield from before as an example.
The morning is clear and bright as the battle lines are drawn. The party stands shoulder to shoulder with their allies, each arrayed against the shimmering horde of their arche nemesis and sneaky mastermind Goblin King Jedvick High Priest of the Great Medvickian Church. The battle formations are tense as the party’s allies are more lightly armored than the heavy cavalry mercenaries siding with Jedvick. The horns of war blare and the battle lines rush toward each other out for blood and glory. As the hours pass and the lines have thinned, each side produces heroes and martyrs, but the struggle continues. Dark clouds roll in and allow the hidden forces from the trees, redcap assassins to sneak into the supply lines and cause havoc but hope is not lost as now upon the field, the outcast tribe of underdark elves join the battle to assist the heroes. The sun no longer plaguing their sensitive eyes they bare down upon the field in a bloody arch. As the scent of blood and sweat reach their zenith a chill wind heralds the arrival of a storm front. In minutes the ground churns into mud bogging down the heavy cavalry of the strategic goblin mastermind. Now is the party’s moment to send a strike team to cut off the head of the snake!
In that description we had progressive stages of effects from changes in light, to general visibility and then alteration of the terrain. Now when the party approaches the boss the GM can say, you are exhausted, visibility is limited to 15 feet in front of you and everything with in 5 feet of you has partial cover. The goblin mastermind may still be fresh having other fighting for him but can no longer stand behind his heavy cavalry as they are now bogged down in the field but will wheel around and enter back into combat if the party cannot defeat their nemesis in 10 rounds.
No matter what level your characters and monsters are, that fight is about to be epic. As a player you can try tactics like kicking mud into the eyes of the boss, sliding through threaten areas more easily with acrobatics but could also be hindered if you are also a heavy armored fighter. Precision damage focused rangers can cut through concealment and keep at range but bards maybe more limited in their inspiration ranges because of the over all din of the battle. Each one of these conditions is reasonable and can be used or bypassed to heighten the experience at the table.
What GMs should be aware of is to balance the mechanical impact of environment impacts so that they do not radically favor either side. Allow the players to have the rewards for any smart and creative counters to the environment but do not stack those effects too heavily in the favor of the antagonist. At some point a party will just not engage if the action is suicide.
One nifty trick you can use with the environment is create moments for antagonists to escape and menace the party again later. The personal guard of Priest Jedvick have been slain. His hidden redcap assassins could not sway the tide against the party but what those fools haven’t seen is the dam upriver that just burst which Jedvick has just spotted. He casts deeper darkness and hops into a barrel as the waters flood the battlefield picking up the barrel and carrying it out past haphazard melee! While his escape is ignoble any battle you can float away from is a chance to build a new army and spread the good news of the Medvickian church!
Unique and clever escapes do not have to just be in the realm of the players and having the environment explain away what is GM magic, can keep the experience fun and memorable for everyone.