Background: was originally from the set Torment. Thematically, Lavamancers are both a) grim and b) iguana fanciers.
Grim Lavamancer is ready to wallop your opponent for 2 damage starting on turn 2, provided you have a way to keep putting more cards into your graveyard. Luckily, this usually happens fast in a red deck, especially if it is populated by aggressively costed cards such as Grim Lavamancer.
MAGUS OF THE SCROLL
Background: A Time Spiral re-imagining of the artifact Cursed Scroll. Nails your opponent for 2 damage starting on turn 3, provided you are willing the pay 3 mana for the privilege.
I assume most people don't (want to pay the 3), which is why it's viewed as a universally crappy card. Because the other requirement, showing a card in your hand, usually isn't a pain come the 3rd or 4th turn. Again…provided you are playing an aggressively costed red deck, full of cards like Magus of the Scroll.
And what if your hand is full of Mountains? You STILL get do 2 damage!