by Mike Shea on 19 March 2012
While the DM cheat sheet works very well for giving you a nice generic dice damage expression at any level and with a variety of situations, sometimes you want a little more control over the dice you might use. Different dice have different stories tied to them. A d8 feels like a longsword. A d12 feels like a brutal axe. A handful of d6s feels like a lightning bolt or fireball.
Being able to select the dice you want led me to build the 4e damage dice calculator. This small mobile-friendly tool lets you pick the level, the modifier, and the type of die you want. In return, it gives you a nice normalized damage expression that follows the updated DMG damage per level rules.
How do you choose the correct multiplier? This depends mostly on your feel as a DM. However, here are a few guidelines for selecting lower or higher multipliers. Each of the multipliers changes the base amount of average damage per level (level + 8).
Minion: Obviously, this damage multiplier works well for minions. It also works well for a larger number of single-use traps or simple harassment damage. It takes a lot of these hits to kill a PC.
Low: This can be used for at-will attacks or continually damaging traps or hazards that hit more than one target. It can also be used for secondary at-will attacks against a single target.
Medium: The default amount of damage that represents an at-will standard action attack against a single target. It can also be used for a limited attack against multiple targets or an at-will attack against multiple targets from a high-damage source like a brute.
High: This represents a limited-use attack against a single target or a single use attack against multiple targets. It might also represent a brute's at-will strike against a single target.
Limited High: This represents a single target single use attack or a limited attack from a high-damage source against a group. The damage is starting to get really high here.
Brute Limited High: This is the most damage at any given level allowed by the rules as written. It represents a single-target one-use attack by a brute.
Hardcore Limited High: This is an amount of damage outside of the rules as written. It can be used for severe damage from a powerful trap.
The decision you come to on choosing a die comes from two questions: how swingy do you want the attack and which die tells the right story.
Since the tool averages the damage anyway, a larger die does not imply higher damage. It only represents the potential range of damage. The smaller the die, the closer to the average the damage will be. The larger the die, the wider the damage range. Some describe this as how swingy an attack is. The bigger the die, the wider range the result and the more swingy it will feel.
The type of die you use can also tell the right story. d6s represent lighter weapons or attacks. d8s speak to longswords, hammers, maces, and medium-sized weapons. d10s feel right for larger attacks such as greatswords or powerful blows. d12s represent huge all-or-nothing blows with axes or the snapping jaws of a huge beast.
The point of this tool is to let you choose the right die type for the story you're trying to tell.