This is my Sedna build for long skilled games. In random/PUG matches, BotF is, generally, a safer option. It's a bit Rook-oriented, but since there is a Rook in 80% of the matches, and it's hard to find a really bad Rook (though I've seen some), that should present no problem at all.
Why AoT/WoS? Sedna is a support DG. To support people, you must be in range. Thus, unlimited freebie tps are a blessing both early (ganks/counter-ganks) and late (portal control, re-locking) game. There is also an icing on the cake in form of zero base travel time.
The single most important purchase here is Wand of Speed. WoS practically guarantees you won't die early/early-mid game, unless your teammates screw up badly. Of course, it also allows you to move swiftly to chase, yellow/prevent yellowing, heal, pounce or silence. At 1750, it's a cheap item, but Blood Sedna, as most other DGs, cannot take it (3 consumable slots typically needed for tps+locks+sigils).
* Unprecedented mobility (!!!).
* Additional item slot (!!!).
Cons (in one sentence: not a newbie-friendly build, by any means):
* Very fragile early game. Relies heavily on WoS for safety spacing.
* Requires a strong lanemate (in descending order of preference: Rook, UB, Occ, aggro-QoT, Erb).
* Requires a good map awareness. AoT is a waste of favor, if you don't watch the map.
Purchase order: 0. Totem, Monks; 1. Cur 1, Scaled, Banded; 2. Wand of Speed; 3. Scaled -> Vlemish + Plenor; 5. Bishops, Unbreakables, Hauberk; 5. Whatever you need: should be another armor, usually.
Skill progression: 1-6 (order may vary according to the circumstances). Heal 1->HW 1->Pounce 1->Heal 2->HW 2->Silence 1; 7. Heal 3; 8. Counter Healing (if unnecessary, you just saved one point, proceed with 9); 9-11. Pounce 2-4; 12-15. Silences, MPs as you see fit; 16-20. Remaining Silences and MPs, Heal 4.
That's how it works early game (nnnils is Rooking on the other side): http://www.gamereplays.org/demigod/replays.php?game=51&show=details&id=219460
A long skilled 3v3 (vs ZennnilsKUSH), reasonably even, with its fair share of nice moments, both early and late game -- involves healing the cit with gadgets, yay: http://www.gamereplays.org/demigod/replays.php?game=51&show=details&id=219461
I'm thankful to hedgie for introducing me into Sed, to McShane for criticizing a low heal build, and, most importantly, to ppapanek for making me reconsider some Western (for a lack of a better definition) Sedna concepts. It's not a rip-off of ppap's Sed, he plays it pure speed usually, but his influence is considerable.