First I must say, great pick for a starting element. :]
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4t4 52g 52g 52g 52g 52g 52g 52o 52o 5i4 5i4 5i4 5i4 5i4 5i4 5i4 5i4 5i4 5i4 5i5 5i5 5i5 5i5 5i5 5i6 5i6 5i7 5i8 5i8 5i9 5ia 5id 5id 5id 5id 8pp
This is the poison deck you posted. I started to tinker with it, because Water and Death have great potential and strong synergies together. The only thing that this pairing really lacks is Permanent control, but poison is there to get around it, so you can survive without it.
Here's what I came up with after some testing with the Elders (ai3):
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52g 52g 52g 52o 52o 52o 52o 52o 52o 52q 52q 5i4 5i4 5i4 5i5 5i5 5i5 5i5 5i5 5i5 5ie 5ie 5ie 5jm 5jm 5jm 5jm 5jm 5jm 5jm 8pk
Yes, I traded some defense cards for more speed and consistent draws, but level3 shouldn't be much of a problem this way.
Swapped some pillars for Water Pendulums and changed the mark to Death. Almost everything you can play is cheap, so this should cover it easily.
Added one Chrysaora, just to have them everytime you need them. It's the main card in your deck, so it's good to have 6 of them.
Replaced the Dragons with Toadfishes, they are cheaper and can be summoned earlier, hit hard for their cost, and even if they die or blocked by a shield the few bites they can bring in helps tremendously with the stacked poison damage.
Added two more Arsenics, but that's only if you've already aquired them. Arsenic is a must have in a deck like this, but adding a few freezes instead (or more Toads maybe), or even Ice shields (though you'll probably only be able to play them later in the game) can fill up that space.
I hope this helped, level3 shouldn't be much of a problem with this deck, as it's fast even with a poor starting hand and none of the Elders are protected from poison.