cards like those do not increase death type spells, only damage type spells. you can only use them on spells such as skeletal pirate or skeletal dragon, actually death damage not convert to half damage
Strong card will not work on my death spells. Does anyone know why. It works on all my other wizards.
If you're talking about the sun spell, then they won't work for the drain death spells (ghoul, vampire, wraith and scarecrow). The reason for this is because drain spells aren't considered as physical damage spells (spells that have fists of them). So, enchantment cards, sun spells like tough to gargantuan and star spell amplify won't work for drain spells. It's been like this since the beginning of wizard101.
"Strong", or other damage boosting treasure cards, can't be used with life-stealing spells such as Ghoul, Vampire, or Wraith. You should still be able to use them on such as Dark Sprite (although it'd be sort of a waste on that), Banshee or Skeletal Pirate.