Rules for building encounters can be found here.
Budget for a standard battle: 5 Monster Equivalents
| Monster level | Standard / 5 mooks | Elite / 7-8 mooks | 2x / large / 10 mooks | 3x / huge / 15 mooks |
|---|---|---|---|---|
| -1 | 0.5 | 0.7 | 1 | 1.5 |
| 0 | 0.7 | 1 | 1.5 | 2 |
| 1 | 1 | 1.5 | 2 | 3 |
| 2 | 1.5 | 2* | 3* | 4* |
| 3 | 2* | 3** | 4** | 6** |
* Be careful. A monster like this might pack an uncomfortable amount of damage into a single swing.
** Probably a mistake to build a battle around monsters that dish out damage like these do.