Masked HERO deck aimed in having every single one of its members, since I'm a Kamen Rider fan. It wasn't made with competitive play fully in mind so it will most likely struggle against the top meta decks. It was also done in Master Duel specifically so keep it in mind regarding some cards like Maxx C, you might want to change them depending on how and where you're using this.
That being said, some cards were added in the extra deck to make it more survivable like Isolde, Sunrise and Absolute Zero. One of the best combos is to summon Absolute Zero (preferably with Liquid Soldier as one of its materials to activate its effect too) and then Mask Change it to Masked HERO Acid. This will trigger Absolute Zero's Raigeki effect and Acid's Harpie's Feather Duster effect, wiping the opponent's field (provided you're able to do it without negation, of course).
• Don't be afraid to send Shadow Mist to the graveyard, but do be careful when you activate her effect in there. Do not special summon her from the GY on the same turn because you can only activate one effect per turn.
• If you ever use Liquid Soldier's effect to draw 2 cards and have to discard one, and you end up with both a "Change" card and "Mask Charge", discard the "Change" card, you'll be able to recover it immediately with Mask Charge (provided you also have a HERO in the GY).
• Contrast HERO Chaos is the ace of the Masked Heroes and you'll want it as soon as possible.
Any comments for improvements to it are welcome, but keep in mind the theme of the deck is to have every Masked HERO in it in tribute to Kamen Rider.