Usually its life, but the first card draw for black was something completely different, something they just dont do anymore
Admittedly hes likely only going to manage to get one batch of Lore before being taken off the field, but when youre only trying to get to twenty points, three can make a big difference
These cards keep your enchantments alive
For example, the Pauper combo shell of Mogwarts (First Day of Class / Putrid Goblin / Skirk Prospector) can create infinite mana and a hasty army
The drawback is that you usually have to pay life to use them but life is a resource, and converting it into actual cards is often a great deal
You usually won't have the mana available to use its effect and when you do, you're better off just winning instead