Card draw is achieved in two ways; looting spells and effects that discard cards to draw more cards, and through repeatable triggers on permanents.
LOOTING
Cathartic Reunion
Faithless Looting
Mask of Memory
Nahiri, the Harbinger
Thrill of Possibility
Tormenting Voice
Looting is the most common way to draw cards in red. The discarded cards are not wasted as many of them can be recurred from the graveyard. Just like the majority of the cards in the deck, the looting spells were chosen for their low mana value. Nahiri is the exception because she can be activated multiple times, has a removal ability and can be tutored for. Mask of Memory can also be tutored and provides repeatable looting draw through combat damage, which is the aim of the deck so it fits well.
TRIGGERS
Esper Sentinel
Puresteel Paladin
Skullclamp
Sram, Senior Edificer
Puresteel Paladin and Sram trigger at different times but both synergise with Equipment being cast or entering the battlefield, which happens often with this deck. Esper Sentinel is just a good card draw in the early game, and Skullclamp is also a sacrifice outlet to trigger Avacyn’s transformation.