I forgot to add that only one Hellmetts card can be used per turn......
'
If you find it has alot of text, I'll tell you what the effect basically is...
1. It's a trap.
2. Use it when the enemy attacks you.
3. Shout "Mettrio!!!" to use the effect or send it to the graveyard.
4. Negate enemy's attack
5. Put a Mettrio counter on that monster
6. Flip this card face down after usage
7. If there are 3 or more Mettrio counters on the field,
8. Destroy all cards with Mettrio counters on them.
9. After that, send this card to the graveyard.
10. Only one "Hellmetts" card can be activated per turn.
Yep, that sums it up.