How about this: a card that creates any of: weak creature(photon, spark, etc), spell(thunderstorm, momentum, etc), or pillar/pendulum.
The element would probably be
or
.
Update:
Or a
card that adds +5|+5 one turn, +4|+4 the next, etc. Destroyed after +1|+1.
Cost something like 7
.
Could name it Time Resonance.