Item 20%
Spell/song (lute) 40%
so far,
60%
Verses of victory wouldn't stack as you've already got the spell haste from the werewolf illusion counting. ATK or STR parts of haste songs DO stack and are worth singing, but the haste part isn't going to get any better and will take the top one, which so far is the Lute's 40%.
Evarj is the V2 so will stack with the spell/song v1 upto cap, so that's an additional 5% (might not be worth singing).
Bringing us upto 65% haste so far.
Vah Shir, being a v3 is going to stack and over cap, but we're not near it, but it's still a 15% haste, bringing us upto;
80% haste for that song selection
Easy these days to get 40% haste items, get a chanter haste for 60%, bang, your at cap. Singing Ervaj's wouldn't help as although it stacks, it doesn't go over the 100% cap.
So,
item (around 40%) + (song/spell/clicky at 60%ish) + v2 (not worth it usually as item+spell get you to cap) + v3 (over cap, that is on the rizlona line, auras, and a very few items just to confused everyone).
There'll be times it's still worth singing haste songs, Warmarch is usually in the twist as although the haste won't add anything as everyone's been clickied/buffed/etc, the DS + ATK will land fine.
And to add even more confusion, the high end overhaste stuff, although it says 30%, turns out the upper limit is 125%.
No wonder it's easy to get confused.