Designing a skirmish encounter starts the same way as designing a regular encounter. Choose a threat and XP budget appropriate for your group. Then, add the troops you want the PCs to have to their side and increase the XP budget by the troops' XP value. For example, if you were designing a low-threat skirmish encounter for a 7th-level group of four PCs, you'd start with 60 XP for the budget If each PC had a 7th-level troop, you'd add 160 XP to the encounter budget since that's the XP for four 7th-level creatures. You would then have a total budget of 220 XP. This still counts as a low encounter, though if you later decide you want a moderate encounter, you can adjust the budget to 240 XP and add more adversaries or increase the level of the ones you have.