Sometimes, the spirits just aren't falling nicely for you and you can't find that one you need for a mission. If you've jumped to three or four beacons and can't find what you're looking for, stop, settle down, and just start attacking everything in sight. Three-star rare spirits tend to give the most xp/energy, and higher HP spirits give the most xp/energy. Sometimes, as with the summer shadows campaign, certain spirits give extra xp/energy.

Figure out the biggest you can take out with your spell pool (one war chant times a low estimate of your average damage (I tend to round down to the nearest fifty) will give you the max HP you should take on) and take them down. Do it until you don't have enough mana left to take out any of the spirits you see and just sit and wait for more to respawn.

You're not fulfilling your missions, no, but you're not wasting time hopping around, and the longer an active mage is in an area, the more spirits spawn around you. Better yet, stay dewarped and do this, so when your beacons come up to be harvested you can grab them immediately. I've often found my campaign rankings do better when I adopt this strategy instead of hopping around, desperately trying to find that one last Drioma to fill a mission.