well, firstly the cyst spider above is one idea. the theme is cancer being empowered by aflatoxin, which causes malignant cells. in light of new cards since that card was produced, mitosis would also be a good choice of spell, given that cell life cycles are *key* in cancer development. like i would say top 5, maybe number 1 overall, biological exploits cancer utilizes in order to survive, generally speaking.
list of target-able spells/skills currently in game to help spark imaginations:
shard of readiness
chaos seed/power
mutation
antimatter
butterfly effect
web
poison
aflatoxin
momentum
gravity pull
devour
chimera
catapult
overdrive
heavy armor
protect artifact
quicksand
basilisk blood
destroy
guard
adrenaline
mitosis
fire lance
explosion
fire storm (not actually targetable, but still)
immolation
rage potion
freeze
ice lance
psionic wave / lobo
nymphs tears (limited)
flood (not targetable, but still relevant)
holy light
heal
blessing
luciderin
endow
sky blitz (again, potentially relevant)
lightning storm (^)
animate weapon
ignite
shockwave
shoot
reverse time
immortality
sundial (just in case..)
siphon life
liquid shadow
nightmare
eclipse
cloak
thunderbolt
twin universe
quint
fractal
silence