If the requirement was 1 Energy less, Swanna would be much more usable, but 3 Energy cards seem like a ludicrous requirement for an attack that doesn't even have a special effect
"Gem-Knight" is the first and, so far, only archetype to boast seven "Polymerization"-styled cards: "Gem-Knight Fusion", "Particle Fusion", "Pyroxene Fusion", "Fragment Fusion", "Absorb Fusion", "Brilliant Fusion", and "Scatter Fusion"
If a creature has the mechanic, that represents two different things: The creature cannot block, and if it ever attacks, it gets sacrificed at the end of that combat
The problem is what happens when someone uses realism to deceive
1x Official counters
And Magic Cylinder is still extremely powerful against the right decks