How about taking on a leader of an enemy team?
Commanders are a tad tougher than Champion type enemies, mostly due to the fact that they are never found alone. They are commanding a team, as their name suggests. They are issuing tactical commands, so the regular units around them use covers more effectively, melee units protect ranged units as long as they are in an advantage.
Commanders can order an assault if their team is weakened, and they can use their buffing abilities to strengthen allied unit. Thus, by taking out the Commander first, the rest of the team can be taken out more easily.
There's but one problem: Commender units are strong, even by themselves. They use 5-8 unique abilities, they can deal a lot of DPS, and they have a higher amount of HP than Champions.
We can encounter such enemies on almost all kinds of maps, usually 1-3 Commander groups.
What's your tactic when facing a fearsome leader? Let us know in the comments!