User blog comment:Sifter66/What makes a late-game champion?/@comment-1330314-20150602062410

As Double Slap mentioned below, exceptionally strong self-synergy or synergy with items tends to make champions very good in the late game. Marksmen are good late game champions in general because the combination of attack damage, attack speed and crit, plus other effects (e.g. life steal, armor penetration...), synergizes incredibly well with itself. The best late-game marksmen tend to be the ones who make the most of those stats. Synergy with specific items isn't that good an indicator, because some items tend to have more pronounced power spikes at different stages of the game (, for example, offers a really good mid game power spike, and champions who synergize well with it, such as or, tend to be strongest during the mid game).

Another indicator of late-game power is the use of effects that become more valuable as the game progresses. Utility and crowd control, for example, is especially valuable later on because it's usually extremely potent in teamfights, which make up most of late-game combat. Damage over time becomes more important than burst as games progress, usually, because DPS will help kill tanky opponents, whereas squishier targets become harder to reach, and therefore burst down, due to those tanky champions. AoE usually becomes more powerful than single-target spells, again because of how teamfights become more common.