Songhai needs draw but not on a zero cost card there are plenty if unused spells they can have draw a card on. Mana vortex seems bad cause now you need to set it up before you play and not just throw it out and have extra cards in your hand.
How mana vortex should change!
There are many small additions that could improve the card without changing its current design.
Mana Vortex: The next spell you cast costs 1 lessā¦
General: Both players draw a card.
General: Your Bloodborn spell is reactivated.
Backstab: Your general has Backstab (0) this turn.
Arcanyst: Play a second Mana Vortex from your deck.
Damage: Deal 1 damage to the enemy general.
My problem with the Mana Vortex nerf is how itās a trap. Just because itās a 0 cost spell does not mean it does not have a resource attached to it. Itās now cleverly disguised card disadvantage. Reducing the cost of your next spell does not do you many favors unless your next spell has an extreme impact and is being played ahead of the mana curve.
I would prefer to see it changed to still provide some additional effect at an increased cost.
Maybe something like:
1 cost
Spells you play this turn cost 1 less
- Allows for dumping/comboing more spells from your hand late game if you can keep cards in your hand
3 cost
Give a friendly minion āWhen you replace a card, your next spell you cast this turn costs one 1 lessā
- Gives potentially long term benefits while keeping a restriction on how many times this effect can be used in a turn.
Mana vortex and siphon Energy nerfs are the worst nerfs that this game has ever seen.
Now this cards are basically unplayable. As gabriek said, mana vortex should target all spell during the turn to be playable now. But se Will never see buff like that:(
Mana Vortex is fine- itās just terribly undersupported (like nearly every Vetruvian archetype :P). You can use it with Koan and Ancestral for value- but the reason it isnāt doing much is because it isnāt fueling something degenerate.
A more productive suggestion would be to suggest a minion or spell that generates Mana Vortexes as part of an ability. Perhaps then we could finally see and bemoan the Triple Spiral deck 
news to me, and Iāve been running all three! 
Seriously. There is no value to be had there. I believe youāre conflating its effect with the value of those other cards, as it effectively lessens the value of those other cards, while still being a net positive overall. In short, itād be better to just play those other cards without Mana Vortex.
How to change Mana Vortex ?
Just change its name to āMana Sparkā.
Because seriously, 1 spell mana discount for zero, itās fuckin far from a āVortexā.
A true Mana Vortex, as I imagine it, according to his name (in fantasy) would be more like :
Cost : 9 mana
Effect : All spells you cast this turn cost 0.
It would be a game closer (if you have a hand), as Obliterate (if you have a creep board) 
Very good point. But cantripping Vortex was very carefully removed for good reasons my manaforging friend
Again, I just really like the idea of introducing a unit that has a trigger that generates mana vortexes so that the card is played solely for Four Winds enabling, and for redundancy and support towards such a minion or spell.
What about those of us who want to use it for making more expensive spells cheaper; ie: the more interesting aspect of Mana Vortex. Sadly, I canāt think of a way to emphasize that part of Mana Vortex without making making it stronger for just general āprocāing a spellā use.
A possible solution would to create a similar mechanism to Power Trip from scrolls, but Iād rather that be itās own card as some kind of variant, as opposed to an errata. IE 6 mana āYour next spell costs 9 lessā. Would make Spiral decks more interesting to say the least.
I like this option as a Songhai player, but as a Duelyst player, I hope this doesnāt get implemented. I also agree that this is a problem as right now, itās actually overcosted, even though itās a 0 cost card.
I honestly think that this is the best solution. A complete rework of the spell is the only real solution, as itās so close to both being broken and worthless.
Four winds magi is annoying enough without spamming zero cost out of deck spell decreasing cards. Mana vortex is a combo card it should be played with other cards so itās fine as it is. What songhai is lacking is reliable in faction card draw. Mana vortex card draw should have been put on another card.
Ancestral Divination and Heavenās Eclipse would like a word with you
AD is a +1 with 2 minions active, and scales up from there. HE is a +2 and one of the spells can be replaced for a minion. Koan is what it is. Not to mention that Xho and Fox generate lots of cards on their own.
Songhai isnāt hurting for card draw :P-- they have more of it than anyone else.
" They really should remove this card ⦠*yawn* "
Thatās what I thought the other day when my dying stupid Xho brought me back a super-discount-one-mana-cost-less ⦠Mana Vortex 
From my limited songhai experience (Iām just saying to u guys abyssians and argeon Lynor are degenerates) I never have enough minions for ad to be worth it over a soujorn or a spell jammer. And no I play kaloes (you know with reva being for degenerates) heavens eclipse was okay I didnāt run to many cause I didnāt have too many spells.
So⦠a better abjucator? Please correct my spelling. Better because 1 - itād be cheaper - 2 it would apply to new spells aquired (from heavens eclipse, lantern fox)
Not in any way shape or form. If you read my post again, I said only for the one turn you cast it. Unlike abjudicatorās discount which is perminent, also abjudicator is a neutral and comes with a body so theyād be very different and good in their own way 
Ah, I see your point.
i.imgur.com/9ai8ICo.png
Triple vortex into Hamon turn 1!
edit: i have no idea how to show images.
To clarify itās a photoshop of vortex to be gain a mana for this turn. Meaning itād now stack with itself and could be used on things other than spells leading to some silly minion ramp.