Dishonored mana, runes and the Heart: a guide for returning players

Coming back to Dishonored after its sequel, three things work differently than you may remember: how mana returns, how you find runes, and how few runes each mission holds.
How does mana come back?
Part of the mana bar regenerates on its own after a power is used; potions restore the rest. Several bone charms change that:
- Spiritual Pool: you regenerate mana slightly faster.
- Spirit Water: drinking from faucets recharges a small amount of mana.
- Blood Ox Heart: your maximum mana is slightly increased.
- Spirited I and Spirited II: potions give you slightly or moderately more mana.
- Falling Star: a drop assassination gives you a bit of mana.
- Gutter Feast: white rats can be eaten for mana.
How does the Heart find runes?
The Heart is "a strange artifact that appears to have a
will of its own", which "leads you toward Runes and Bone Charms, whispering
secrets along the way". Equip it and it beats faster as you near a rune or charm.
Its first use is an optional objective in
High Overseer Campbell: use the Heart to
find the rune near the Hound Pits Pub.
How many runes does each mission hold?
Each mission's end screen counts the runes found in it. High Overseer Campbell lists 7, House of Pleasure 5, The Royal Physician 5, Lady Boyle's Last Party 3, Return to the Tower 4, The Flooded District 5, and The Loyalists and The Light at the End 1 each: 31 in all, with more outside those totals (the Outsider's gift in the dream, and the rune handed over at the Hound Pits after Lady Boyle's party). Piero's Shop sells one more for 500 coins.
Buying every power and enhancement level costs Corvo 58 runes, so a single playthrough cannot buy everything. Plan the build before spending: the rune planner totals a build with its prerequisites and names the mission after which it is in reach, and the rune guide compares Corvo's prices with Daud's.
Does Dishonored have New Game Plus?
Dishonored's own menu offers New Game only; runes and powers do not carry into a second playthrough. Dishonored 2 and Death of the Outsider added Mission+, which replays a finished mission with every power available.