Well QoT was my first DG, so I know pretty much about her. Back in the time, she was considered by many to be one of the overpowered. Feeling Cheap, I stopped using her for sometimes. Now I retry her and let me say, she is pretty bad.
Before they move the HoL, she had been "nerf" once. All of her spells costed more. I remembered that I could cast shield 3-4 times, but now, only twice before going base.And now that they moved HoL for a ridiculous amount to the artifact shop, the previous nerf still persist on her. Her spells are still mana loaded and without the help of the HoL.
Her Open Form lacks everything. For the ability to cast AoE, she lost regen and armor. If ganked, she has no to little chance of survival. While in close form, she can still rely on shield and the minor armor boost.
Her summons are pretty bad. For a range summon, they cannot avoid tower range or even get near enough to attract the beam without hurting the QoT which has about the same range. They have less life and numbers than Nightwalkers, they have less mobility and spawning force than Oak's Spirits and they do less damage than Yeti (which are also pretty bad) with no level 15 boost like the Yetis.
OF ALL DEMIGODS, she is the only one without any interrupt. Even Regulus has a 3% stun at lv 15, while her arch rival (the other support dg) Sedna has two interrupts herself alone.
The entangle skills is worthless, it doesn't stop the tower's beam while Rook's tower eating does. It does less damage than Spike+damage per second. And worse, the cooldown doesn't make it any effective. I mean... UB's spit is about the same damage and less cd overall AND IT CAN TARGET DG.
Many of her skills line are there to upgrade another skills (3 of them?). Their passive relies solely on the summons without any lv 15 passive great bonus. +4 gold as a lv 15? By then, the game is almost done.
Oh and... Low Stats Growth.
Only Rook is slower than her.
Worst hp. Worst armor. Worst normal hit DPS.
With two helms and one boot (~1.5k each) you will be out of mana in one fight, while others aren't.
So ya. Suggestion?
Open form more DPS, more max health and mana.
Summons able to interrupt, greater range, when dead by enemies, spawn into two smalls once, which cannot be eaten.
More HP.
Passive that increase other skills (spike? plz)
Less mana used.
When eating the summons, get mana also.
Remove entangle, or make it to immobilize dgs too, while not stunning them.
Anyway. I hope any changes would "buff" her a little bit.