I would so run a modified SoP-sparktal with these and nova / cremation..
actually, that could work well just replacing the sparks with these. Super nova would power 6 a pop... cremation could power about 4 to 5 each.
Just use dim shield till you can get them high enough to knock the opponent down to a few hitpoints and sac all but the one you need for the finishing blow.
They are UP for self-sacrificing means. Only their HP is what can be abused. Sparks are different story, they have some attack power at least.
Wait a second, is it the creature's HP that is used to calculate the electrum gain (or HP + Attack), or its casting cost?
I thought casting cost was it.
If its HP and / or attack, then its a relatively mute point anyway. SoP will be ramping up bot attack and HP so you would have a good return in either case.