Like them, but some suggestions:
Dread: Yikes. Not sure how to nerf it without ruining it, and I know fiendish/effect veiler/any destruction or removal spell or trap is a counter, but with Jinzo Dragon's Glare/Royal Decree this thing has the ability to create a near lockdown, forcing the opponent to pray they can topdeck a veiler or dark hole if its attack goes through. They can't even Battle Fader or Gorz because no SS (At least, I think that's how it works). Semi-limit or plain Limit.
Last Hope: Basically dark hole, but with burn added. Lots of burn, in many cases. Maybe make it so it can only be used on one effect monster a turn and sends to the grave instead of destroying (bye bye Beelze and Garunix), or destroys the whole field except itself for half the damage it would deal normally if there are three or more monsters on the field and at the cost of both materials?
Goddess: JD is best field nuke (not really, but it's my favorite). The secondary effect is actually a well balanced, good effect, but seems it could be abused being used immediately after a field nuke (Cyber Twin Dragon or something similar) so maybe have it not be able to attack the turn it's summoned? (Other Dragon God cards could still attack, though.)
Final Storm: Might want to change it to "All face-up effect monsters". Maybe have it be the only one that can attack the turn it's summoned.
Forceback: Maybe add "If you control a monster with Dragon God in its name"?
Dragon's Glare: Dread+this=Near-perfect lockdown...
Devourer, parasite, Efreet, Rage, Domain, Fallen One and Water Spirit are well balanced IMO.
FUSION SUGGESTION---This card may attack all effect monsters your opponent controls once per turn, and if this card is targeted by a spell or trap card's effect, you may special summon one card used as a fusion material to summon this card (either banished or in the graveyard) It may not activate it's effect but may not be destroyed this turn.
Water spirit plus any other Dragon God monster, 2600ATK, 2100 def.
Overall, just needs some slight balancing fixes. Keep in mind, I'm not trying to bash or seem "superior" in card designing just trying to give constructive criticism. I'll probably make cards and archetypes relatively soon, so you can give me advice too. BTW, if you take some time to learn some scripting stuff, you can test these on DevPro.