Don't increase cost of ability when upped. Don't know if ability is too costly. Hard to splash this in a rainbow (which ability necessitates), cost is too high
Consider that ATK is more valuable than HP. Then the buff is worth less than Eclipse (which has in element synergy). Then the ability, priced as it is, is itself cost enough besides the cost of the permanent. This could cost 3|4 or 3|3
Useful in a death stalker deck in that having 5 copies of this doesn't make later copies a dead card