[Coda]

I dunno if I've posted my recommended Extreme King Metal Dragon strategy here before. Might as well:

Leader options: Grape Dragon, Snow Globe Dragon Noir, Lucifer
Strong poison: Cleopatra, Neptune, AB Bluebird Blues, red Odin, red Odin Tamadra
Defense break: non-Awoken Shiva, Top Droidragon
Dark-element Gravity: Divine Queen Hera, Awoken Hera-Is
Dark-element RCV: Lilith, Valkyrie Claire, Persephone

I personally run Grape Dragon - Cleopatra - Top Droidragon - DQ Hera - Lilith - Lucifer.

Ginny runs Grape Dragon - Shiva - Neptune - DQ Hera - Lilith - Grape Dragon.

The basic strategy here is that you need tons of HP and RCV, and the only straight-up offensive power you need is a single spike in the last round.

Round 1: Charge skills.
Round 2: Use strong poison.
Round 3: Charge skills.
Round 4: Use strong poison.
Round 5: Use Gravity, use defense break, nuke.

If you don't have a good defense break, you can use a weaker poison in round 4 (e.g. Lilith) instead, but then you have to be more careful with your HP.

Technically, Gravity is optional, it just reduces the damage output necessary in round 5; you could substitute a different active skill as long as you can deal with the defense.