What about lowering attack with the semi-lobo?
Something like "Target creature loses 1 attack every turn while attack is greater than 0. If the creature also has a skill, its skill cost increases by 3 quanta."
This would be stackable, so after two Heavy Loads a creature would be losing 2 attack per turn and its skill cost would be 6 higher than normal.
Would be mostly good for targeting creatures with low/average attack but useful abilities, since one card can nearly render them useless. Leaving creatures out on the field like vegetables would also be good for avoiding death-triggered tactics.
Some other ideas to consider are making the skill cost gravity quanta if it has no specified element cost along with the increase (such as after a SoR use), making it grant a particular skill based on the dead weights to a creature if it has no active skill (not sure what), and/or making it delay the creature it is played on for 1-2 turns. Giving it both a delay type effect, 'and' a semi-lobo effect could work.
I just figured it'd up cost by what it used to be. Are there creature skills that start with no cost? (Ignoring SoR)
Delaying sounds good too, it's probably going to be either this or the idea at the top of this post (assuming it actually works).
Sorry for throwing around so many ideas - I'm still trying to figure out what works and what doesn't.