A Beginner's Guide to Team Compositions
Hello!
Through my adventures in soloq, I have noticed that a lot of people don't really care about, or work towards the win conditions of their team comp. This thread is here to not only inform you that team comps exist, but also to tell you what champions might work well in a specific team comp. If you see your first pick lock in a pick, it might be worth your while to build a team that will synergize with said pick.
With that being said, many comps can overlap, and many champions can fill multiple roles. Comps in League of Legends are also not limited to those described below. This is intended as a general guideline, and not as a be-all, end-all to teams.
If there is anything that is here in error or missing, please point it out in the comments.
POKE/SIEGE COMP
These comps excel at whittling down enemies from afar, before closing in for easy kills or objectives. Siege comps in particular are focused on taking down towers by forcing away enemies with poke, while sneaking in autoattacks on the towers whenever it is safe.
CHAMPIONS THAT EXCEL IN POKE/SIEGE COMPS
In general, ranged champions fare better in poke/siege comps than melees, as they have an easier time hitting towers safely. Sustain is also an important consideration, for the more sustain you have, the more likely it is that you will outlast your opponents with poke.
DIVE/ENGAGE COMP
These comps excel at forcing fights, starting them with lots of CC from the tanks and bruisers in order to leave enemies helpless against the relentless onslaught of your team's carries. These comps create the most "wombo combos", and can often win fights with a good engage, even when behind.
CHAMPIONS THAT EXCEL IN DIVE/ENGAGE COMPS
AoE is the name of the game in these comps. The more damage you can do more targets while they are all incapacitated, the better.
CHASE COMP
These comps excel in extended engagements, running down kills in open spaces with ease. They will clean up most low-hp targets after teamfights. Since these champions are all mobile, they are good at escaping from sticky situations. Many of these champions can be found in competitive play.
CHAMPIONS THAT EXCEL IN CHASE COMPS
Since these champions are all mobile, they are good at escaping from sticky situations. Many of these champions can be found in competitive play.
STALL COMP
A common factor of stall comps is that they contain one or more late game carries that need time to ramp up. The time required for this ramp up is bought by a strong waveclearing presence, preventing the opposition from pushing and ending the game before your late game champions are relevant. Champions with a strong disengage potential are also very useful to prevent fights before your team is strong enough to take them.
CHAMPIONS THAT EXCEL IN STALL COMPS

PICK COMP
These comps excel in finding isolated targets, and blowing them up in order to gain an advantage. High burst is a necessity.
CHAMPIONS THAT EXCEL IN PICK COMPS
You will notice that pretty much every assassin in the game is on this list. That is because assassins excel at blowing up single targets, which is exactly what this comp does. Vision control is extremely important when playing pick comps, for if your entire team is sitting in a warded bush, you're just wasting time and giving up free objectives.
I hope you found this guide informative, and that you will pay more attention to the strengths and weaknesses of your team moving forward.