Ah. So looping is allowed? I dunno. Would that make this OP then? Consider,
Steam machine needs 2
for basically +4|+0
Lava golem and forest spirit need
or
for +2|+2
Fire spirit and fire eater need
for +2|+0
All those above can only be used once per turn.
Excelsior needs an initial 2|3
investment, and then 2
for +3|+3, and it can be used multiple times per turn. With 6 light pillars, you're getting a 4|4 creature that gains +6|+6 per turn.
also isn't that hard to amass with fractalrol, and solar shield.