This build is for players who want to play with minions.
The key is that the first few skills are for an assassin type build. The advantage of this is that Minion builds are weak at the start and are best used when your opponents are not speccing for AOE. Also, her starting assasin type skills even at level 1 are key through the whole game and very mana efficient, meaning you don't have to spec so much for mana.
This build is quite cash intensive, dont be fooled into thinking that Sedna requires no money and can just buy cit upgrades.
Blood of the Fallen - Most of the time, especially if you are unsure of opponents.
Ring of Divine Might - This is especially useful for clearing out creeps, but is more for late game.
Cloak of Night - Very useful for Sedna, allows for you to overextend from your minions then teleport back to your priests.
Early game (levels 1-4)
Take priests from the store. With the current game, these should be sold back and then Banded Armour purchased, taken with a teleport scroll and Flag lock or just save the cash.
Heal - Take Heal first, this is a great skill and will be used all through the game. It is great for a pinch.
Inner Grace or Healing Winds - Take Inner Grace first if you are on your own holding a lane. Take Healing Winds first if you are supporting a teammate.
Pounce - Take this next, at the start it is of limited use, as your mana is going to be low, you can't spam Heal and Pounce. But it is valued for it's interrupt.
Inner Grace or Healing Winds - Take which one you didn't before.
General play is try to conserve your priests, you don't want to have to repurchase them.
Switch Time (levels 5-10)
You have decided that your oppnents are not going large scale AOE, you are not stack against an Angel Reg, Ooze UB and a TB. Time to switch to minions. If you see that minions are going to have a hard time, stick to an assassin build.
If you have some cash and don't need to get Gold upgrade by this time. Remember to upgrade your priests and possibly get ranged minions, then get a Vlemish Helm.
Magnificent Presence - Take this first to boost your priests a little, also gives you a great cooldown bonus.
Healing Winds 2 - Gives you great regen.
Yeti 1 - Why so late? Well now your Yeti when he appears will be a lot better prepared. You are mana light, this takes up 550 mana to summon one! You want it to last. I would even recommend holding off summoning it, unless you are near the mana crystal.
Yeti 2 - A little better, you can get two at a time. Try to resummon at the crystal still though.
Yeti 3 - Now they are starting to rock.
Yeti 4 - Snowball attack!
At this stage, you should be plugging your cash into Minion related items, upgrading to Bishops and Sieges are your best bet. Hauberk of Life, if doing really well for cash then pick up Theurgist Cap. If a little lower, then Forest Band can be worthwhile. Or just stick to Armour like Nimoth Chestplate.
Also, even your level 1 skills of Heal and Pounce are still effective at this stage, so waiting for minions does not hurt too much.
Mid Game (levels 11-15)
Magnificant Prescence 2 - This also allows you to get those level 1 spam abilities off quicker.
Inner Grace 2 - Time to spend some time on yourself
Inner Grace 3 - Now you are speedy!
Morale 1 - A little minion love
Wild Swings - Your little Yetis are loving it.
Now here is a little more flexible. You may want to substitute these skills for Counter Healing if the priests come out sooner. I don't really advise going Silence, it is too mana hungry, this is great for a support build, but for a minion build too mana intensive.
Upgrade your items. You should definately have the minion idols permanantely slotted, even the most micro intensive management they will still die eventually. If you can get an artifact by now, then go Girdle of Giants or Bulwark of Ages, these really complement Sedna well.
End Game (15-20)
Magnificant Prescence 2 - Those minions are rocking!
If you really feel the game with minions is not going well, you could try to buff up your Heal or Pounce skill. However, it still means that you are burning more mana than you can afford. You will be resummoning minions as they die.
Get the armour artifacts and you will be mostly unstoppable.
This build is great as a defensive wall. You can hold a lane and be very self-sufficient.
You need to be aware of what you are there for though. This build is best for taking down towers and helping your creeps push. It also works well in support, your priest minions will heal your teammates, for free, and you have some emergency healing you can spam and interrupts to stop other skills.
You should be picking up a lot of assists, don't expect to get a lot of kills. Your minions are slow and will be outrun by a wheezing Rook going uphill with a headwind. Try to get behind enemy DGs so they have to run through you, you have no snare so you can't keep them in range. They won't be likely to be coming back your way though, as killing a HP regenning Sedna surrounded by a mini army is too hard.
This build is a lot of fun, your kill deaths won't be so impressive, it may not be quite as powerful as the assassin build, although the assassin build will not be ripping down towers like candy. Against an assassin build Sedna you actually most probably have more chance. You will be outputting more DPS, and heals are easily enough stunned. Likely neither will die as running away is too easy!
You can split your minions off and send them elsewhere, this is great if you are unpressured or just strolling back to the citadel.
Teleporting - This will take your minions with you. I normally recommend walking back and leaving your minions in place to help your teammates. If they are dieing, simply resummon at crystal then tp back with them.
Stick to Armour and Health items, if you die your army goes with you. Try to conserve them early game so you don't need to waste mana recasting. Don't go big mana spells as this means you cannot get minion beneficial items, having to use mana regen instead.
Feel free to tweak!