Once upon a time I was running a game where a gang of goblins had overrun a border plantation, driven out those lucky enough to escape, and set up the manor house as their own personal fortress.
My player, the halfling and the wizard, decided to take a side mission and investigate the trouble, at the behest of a henpecked middle aged farmer and his overbearing sandal-weilding wife.
They made their way carefully through the crops, using the tall wheat to mask their advance, and got the jump on an outlying patrol, slaughtering them and getting some intel in the process.
They approached the main manor and found they area around the building was flat and open (originally for moving wagons around and for gatherings) and had been cleared of obstructions, leaving a wide open space maybe fifty feet in a all directions. In addition, there was at least one sentry posted that they could see from the concealment of the grain.
The building was two stories and wooden, with a southern style wrap around porch and lots of windows.
In military terms, the goblins had cover, a clear field of fire, and an established kill zone.
The players attempted to snipe at the sentry, so they could approach quietly, but missed. The alarm was raised and the battle was joined.
Archers appeared in the upper windows, and a small skirmishing force attacked from the ground floor. These were just goblins though. No big deal, right?
The players lured the skirmishers into the grain and massacred them, but quickly found themselves unable to advance and heavily outgunned at range but the archers.
Then the goblins brought out their ace. The door opened and they rolled out a small ballista with a crew onto the porch. It had been held centrally in reserve inside so it could be deployed in any direction.
Yes, this is the goblin ballista story.
The players decided they were heavily outmatched at range (even though they specialized in bows and slings themselves) and they didn’t have any powerful offensive magics available to them. Rather then retreat, they charged.
The halfling charged across the open field toward the ballista without the benefit of smoke or darkness and the ballista took it’s shot.
Roll: Confirm Crit
Roll: Almost max damage
As it stood the halfling was going to have a hole in him big enough to see daylight through and the wizard was going to be in no position to safely rescue him without getting perforated herself. He was going to die.
There are several schools of thought on how the DM should roll. Some roll behind the screen because it allows them to fudge the dice when needed and keep the players alive when the story requires it.
I am not that DM. I always roll in the open, and at the beginning of the game, before character creation I make it clear that the dice are rolled in the open, and if they say you die, then that’s what happened. There’s no harm in running a game like that, provided the players understand how the game is run ahead of time, and make their decisions based on that.
One of the drawbacks of rolling in secret is that when the dice do roll hot, and the players get in trouble, the players can always foster the suspicion tht the DM is out to get them, because things are hidden, and they could be literally anything.
Quantum dice are nobodies friend. I strongly advise rolling in the open. It keeps the hits and damage as the fault of fate, rather than a malevolent and fickle DM. Rolling in the open can save friendships.
With those parameters established, and a character’s life on the line, we referenced the books, the supplemental books, and online commentary.
It turns out, unbeknownst to me, small creatures get a listed -4 to hit when using a ballista. There’s no explanation given, just a flat penalty, and that was enough to turn the confirmed crit into an unconfirmed crit, and saved the character from instant death.
The halfling cleric healed himself, finished charging across the field, and slaughtered the goblins to a man.
Some might say the encounter was to hard, but in reality the goblins were monster manual stock goblins, with the only modification being the ballista crew, which needed their feats and skill shuffled to allow them to actually use their equipment.
Goblins have a CR of 1/3 so a small group of 12 should have been easy peas for a pair of level 3 characters. They just got lucky and had above average positioning.
Rolling in the open can prevent the suspicion of persecution, and can prevent a lot of social drama. Social drama isn’t fun, and the most important rule is “Have Fun!”