Remathilis
Legend
I voted 7 each, but on reflection 10 sounds right. Here me out.
If you look at levels 1-3 on the playtest, the primary way PCs level up is via damage output. Rogues (appear) to gain Sneak Attack dice almost every level. Fighters gain weapon focus damage every level or so. The main way clerics and wizards gain damage is via increase in spell level. Spells themselves don't improve with level (magic missile being the exception) so to keep up, casters will gain access to a new round of spells every other level (1, 3, 5, 7, 9, 11, 13, 15, 17, 19).
Burning Hands (lvl 1) does 2d4 + Int to radius
Arc Lightning (lvl 2) does 4d6 + Int to a target
Fireball (lvl 3) will do 5d6+ Int to a radius
and so on.
If you look at levels 1-3 on the playtest, the primary way PCs level up is via damage output. Rogues (appear) to gain Sneak Attack dice almost every level. Fighters gain weapon focus damage every level or so. The main way clerics and wizards gain damage is via increase in spell level. Spells themselves don't improve with level (magic missile being the exception) so to keep up, casters will gain access to a new round of spells every other level (1, 3, 5, 7, 9, 11, 13, 15, 17, 19).
Burning Hands (lvl 1) does 2d4 + Int to radius
Arc Lightning (lvl 2) does 4d6 + Int to a target
Fireball (lvl 3) will do 5d6+ Int to a radius
and so on.