Then don’t kill off humans to transform it, deal damage directly to it instead, thus expediting the transform. Especially in a red deck, it can transform within a few turns with the proper cheap mana/high damage spells like:
Processor Assault ~ 1 mana cost + process 1 = 5 damage
Lightning Axe ~ 3 mana cost + discard last card = 6 damage
Fiery Impulse ~ 4 mana cost = 2 damage (or 3 if there are more than 8 red gems)
From here the ratio of mana cost to damage is a little more even, or verging on more mana then damage however they’re still useful.
Outnumber ~ 8 mana cost = 2-8 damage depending on how many creatures you control on the battlefield when the spell is cast (normally 2-6, however if you have used something like Malevolent Whispers or anything else to temporarily steal one of your opponents creatures, bringing you to 4 controlled creatures, it does successfully ramp up the damage caused)
Stonefury ~ 10 mana cost = 5 damage
I’m positive that there are many more out there, some that could cost less, as well as some from other colors, however I’m just going off of what I currently have available.
I’ve long since abandoned trying to getting it to transform by killing the creatures created by it, and instead deal damage directly to it, or (when it was working correctly) throwing a spell on it such as Haunted Cloak (Colorless spell with a 1 mana cost, that gives Vigilance, Haste and Trample to target creature) thus making it defend against any/all of the opponent’s creatures, which ensures a very rapid drop in that 35 defense.
Unfortunately one of the recent updates has made it become disabled until it transforms for any attack/defend abilities, thus that last option is now useless, however there is no mention of it supposed to not be able to defend/attack, and has been reported as a bug with the card by quite a few people, thus that may return. Before the bug hit it, with simply the Haunted Cloak on it, I could usually get it to transform within 2-3 turns depending on how many creatures the enemy brings out/how many direct damage spells/abilities I could throw at it.
I HAVE been able to get it to transform the same turn I cast it ONCE, however I had a bunch of direct damage cards saved up specifically to transform it ASAP.