As suggested the standalone cost for Hellspawn is now 5 and Elite Hellspawn remains at 4 . Also increased spawning cost to 4 , with Elite Hellspawnl at 3 reflecting its lessened standalone cost.
I miscommunicated. However I like the solution you used.
However it is important for you to know that Elite Hellspawn's reduction in cost comes from it being upgraded.
The spawn skill only takes the value(cost without upgrade bonus) of the spawned creature not the cost of the spawned creature into account.
A reduction in activation cost from 4 to 2-3 would increase the cost of the upgraded Malebolgia by 1.
However the upgraded Malebolgia gets an upgrade cost reduction as well which cancels out the increase.
So it worked out fine but not for the reason you thought.
Now there are just two things left.
1) Get provably non copyrighted art ASAP even if it is a crappy drawing you make in paint.
2) Discuss if the aggro ability deserves a cost increase or not.
Typo: You unupped Hellspawn image does not have the correct attack