How much spell power do casters need to match Classic damage?

In the Forever beta, base damage on caster spells dropped a lot while spell power coefficients went up, so damage catches up as you stack spell power. Below is the extra spell power Forever needs to reach Classic's base damage (at 0 spell power) — level 60, highest rank, DoTs over their full duration.

What it means

• Priests and Mages mostly need +70–80, which early gear covers quickly. Mage fire spells are the exception (Fireball 211, Scorch 179, Pyroblast 172).
• Warlocks lose the most on their core spells — Immolate 419, Soul Fire 366, Corruption 320 — while Drain Soul and Siphon Life barely change.
• Druids and Shamans are hit hardest. Chain Lightning needs +715, so the gap is biggest while leveling and in early gear.