While the strategy has risen in popularity recently, the idea of BLM 2nd against Night Elf is no new idea. It is something we have seen being played sporadically throughout several years. Falling short by just a little. So, what has changed?
With patch 1.30.0, Demon Hunter (DH) got 1 agility less and Riflemen got a +11% attack speed buff, thus empowering the already existing tier 2 power spike for Human. This – alongside the nerf on Militia duration – made a committed timing-attack on one base very attractive for Human, instead of relying on an expansion. With Keeper of the Grove falling out of meta in favor of DH with patch 1.31.1, the meta for Human quickly became Archmage with NSW, trying to take full advantage of the power spike before a critical number of bears is a possibility.
Thanks to Frost Arrow, NSW’s impact does not rely on having a lot of mana, making her an obvious choice against DH. Likewise, BLM also does not rely on having a lot of mana as he is usually picked for Siphon Mana. The impact of having Siphon Mana might, however, not be as immediately obvious.
Against Panda, BLM makes a lot of sense. Panda has scary abilities, so denying him from using them is good for you. Plain and simple. But the meta for Night Elf is DH and NSW. Neither really rely too much on their mana anyways.
By stealing the mana of NSW and DH you deny them from using their abilities and you make restoring health through Moon Wells a bit more costly. Both points are of course positive, but neither are the main reason for BLM’s strength in the matchup.
The crucial factor is that all mana stolen from the enemy can be routed back to the Archmage for additional Water Elementals. If Dryads get the time to regen mana, Abolish Magic easily deals with Water Elementals, but with a well-timed attack, Water Elementals are of monumental impact.
Normally the Night Elf will tech immediately to tier 3, making resources for Dryads very scarce. Well-aware of the many incoming Water Elementals, Moon delayed his tier 3 tech a lot in his first game against Infi. This gave him the needed dispel and firepower to hold off Infi’s timing attack. Realizing that there would not be any Bears to deal with anytime soon, Infi added in Mortars to fight the Dryads which made the second push lethal.
As the general idea of a push with NSW and BLM is the same, the differences between the two are subtle. With BLM you are much more reliant on Archmage being level 3 before push. If you are not level 3 as you do the push, you will not reap the benefits BLM gives properly.
Another noteworthy difference is lock-down. Without having Frost Arrows, you are solely reliant on Sorceresses to slow down DH. Infi therefore gets a Sorceress immediately after the first Priest, whereas you can afford to delay it a bit more if you are playing NSW.
If you are looking to learn the push, I recommend studying some replays of Infi as he seems to have the push down to a tee. While you can best learn all the details from replays, here are some of the key things he does that I personally find interesting.