level 1 smoke signals level 2 the summoner level 3 a familiar foe level 9000+ a sacrifice of flesh. you are confusing "level" and "tier"
oh and if the pattern holds, the next eb will actually be easier than this one. the level one eb of a new tier is usually easier than the top level from the previous tier.
go look at a clan that doe tsg/ss rotation. ss is always done in less time. ss is the easier of the two. the clan killa is a great example.
Difficulty isn't just time. It's easier to hit TSG, and the comparing just time is inadequate. You have to compare time relative to how long it is. 6 hour ss = 8 hour tsg. If SS is done in 6 hours, and tsg is done in 6 hours, tsg is easier. However if tsg is done in 8 hours, they are equal.