Rescale MR artefact property from 35-99 range to 40/80 steps

Easier to compare to other MR items, more clear in the interaction with
MR resistance line on %, gets rid of shops approximately leaking the
amount of MR, and also removes a special-cased inscription handling.

{MR+} now indicates 40 MR across the board, {MR++} stands for 80.

Almost all MR unrands had to be adjusted one way or the other. Several
of them had MR in the range 30-50 and were converted to {MR+} (40 MR).
Exceptions and other changes are listed below:

- Bear Spirit: buffed to 80 from 50
- Chilly/Flaming Death: buffed to 40 from 20
- Elemental Staff: buffed to 80 from 60
- robe of Folly: buffed to -80 from -100
- Four Winds: buffed to 120 from 100
- Jihad: loses its 20 MR
- ring of the Mage: buffed to 80 from 50
- Spriggan's Knife: buffed to 40 from 20

1 files changed, 25 insertions, 26 deletions

diff --git a/crawl-ref/source/art-data.txt b/crawl-ref/source/art-data.txt
index f78bdccfe2..1eef357244 100644
--- a/crawl-ref/source/art-data.txt
+++ b/crawl-ref/source/art-data.txt
@@ -136,7 +136,7 @@
 # EV:       Evasion modifier.
 # FIRE:     Fire resistance/vulnerability.
 # INT:      Intelligence modifier.
-# MAGIC:    Magic resistance modifier.
+# MAGIC:    Magic resistance/vulnerability.
 # METAB:    Hunger modifier.
 # MP:       Mana capacity modifier.
 # NAME:     Name of artefact when identified.
@@ -335,7 +335,7 @@ BRAND:   SPWPN_FLAMING
 FIRE:    2
 COLD:    -1
 BOOL:    poison
-MAGIC:   20
+MAGIC:   1
 
 NAME:    mace of Brilliance
 OBJ:     OBJ_WEAPONS/WPN_MACE
@@ -371,7 +371,7 @@ TILE_EQ: chilly_death
 BRAND:   SPWPN_FREEZING
 FIRE:    -1
 COLD:    2
-MAGIC:   20
+MAGIC:   1
 BOOL:    poison
 
 NAME:     dagger "Morg"
@@ -382,7 +382,7 @@ TILE:     urand_morg
 TILE_EQ:  morg
 BRAND:    SPWPN_PAIN
 INT:      5
-MAGIC:    30
+MAGIC:    1
 
 NAME:    scythe "Finisher"
 OBJ:     OBJ_WEAPONS/WPN_SCYTHE
@@ -440,7 +440,6 @@ TILE:     urand_jihad
 TILE_EQ:  jihad
 BRAND:    SPWPN_HOLY_WRATH
 EV:       3
-MAGIC:    20
 ANGRY:    3
 STEALTH:  -50
 BOOL:     life
@@ -454,7 +453,7 @@ TILE:    urand_hellfire
 TILE_EQ: crossbow_fire
 FIRE:    2
 COLD:    -1
-MAGIC:   40
+MAGIC:   1
 BOOL:    evil
 
 NAME:    sword of the Doom Knight
@@ -464,7 +463,7 @@ COLOUR:  BLUE
 TILE:    urand_doom_knight
 TILE_EQ: doom_knight
 BRAND:   SPWPN_PAIN
-MAGIC:   50
+MAGIC:   1
 BOOL:    nospell
 
 NAME:    morningstar "Eos"
@@ -498,7 +497,7 @@ TILE:     urand_octopus_king
 TILE_EQ:  trident_octopus_king
 BRAND:    SPWPN_VENOM
 BOOL:     elec, poison
-MAGIC:    50
+MAGIC:    1
 
 NAME:    mithril axe "Arga"
 OBJ:     OBJ_WEAPONS/WPN_BROAD_AXE
@@ -508,7 +507,7 @@ TILE:    urand_arga
 TILE_EQ: arga
 BRAND:   SPWPN_SPEED
 STR:     2
-MAGIC:   30
+MAGIC:   1
 
 NAME:     Elemental Staff
 OBJ:      OBJ_WEAPONS/WPN_STAFF
@@ -518,7 +517,7 @@ TILE:     urand_elemental
 TILE_EQ:  elemental_staff
 FIRE:     2
 COLD:     2
-MAGIC:    60
+MAGIC:    2
 AC:       5
 BOOL:     elec
 
@@ -575,7 +574,7 @@ TILE_EQ:  spriggans_knife
 BOOL:     tilerim
 EV:       4
 DEX:      4
-MAGIC:    20
+MAGIC:    1
 STEALTH:  50
 
 NAME:    plutonium sword
@@ -702,7 +701,7 @@ TILE:     urand_bear
 TILE_EQ:  bear
 BRAND:    SPARM_SPIRIT_SHIELD
 BOOL:     life, berserk
-MAGIC:    50
+MAGIC:    2
 
 NAME:     robe of Misfortune
 OBJ:      OBJ_ARMOUR/ARM_ROBE
@@ -780,7 +779,7 @@ TILE:    urand_resistance
 TILE_EQ: shield_of_resistance
 FIRE:    1
 COLD:    1
-MAGIC:   40
+MAGIC:   1
 
 NAME:    robe of Folly
 OBJ:     OBJ_ARMOUR/ARM_ROBE
@@ -791,7 +790,7 @@ TILE_EQ: robe_red2
 BRAND:   SPARM_ARCHMAGI
 INT:     5
 CURSED:  3
-MAGIC:   -100
+MAGIC:   -2
 
 ENUM:    MAXWELL
 NAME:    Maxwell's patent armour
@@ -801,7 +800,7 @@ COLOUR:  LIGHTGREEN
 TILE:    urand_maxwell
 TILE_EQ: maxwell
 BRAND:   SPARM_PRESERVATION
-MAGIC:   50
+MAGIC:   1
 BOOL:    nospell, notelep, cursed
 
 ENUM:    DRAGONMASK
@@ -810,7 +809,7 @@ OBJ:     OBJ_ARMOUR/ARM_HAT
 COLOUR:  ETC_SHIMMER_BLUE
 TILE:    urand_dragonmask
 TILE_EQ: art_dragonhelm
-MAGIC:   40
+MAGIC:   1
 ACC:     3
 DAM:     3
 BOOL:    seeinv
@@ -821,7 +820,7 @@ PLUS:     +4
 COLOUR:   ETC_DARK
 TILE:     urand_night
 TILE_EQ:  robe_of_night
-MAGIC:    30
+MAGIC:    1
 STEALTH:  50
 BOOL:     seeinv, inv
 
@@ -831,7 +830,7 @@ PLUS:    +9
 COLOUR:  ETC_GOLD
 TILE:    urand_dragon_king
 TILE_EQ: dragonarm_gold
-MAGIC:   50
+MAGIC:   1
 
 NAME:    hat of the Alchemist
 OBJ:     OBJ_ARMOUR/ARM_HAT
@@ -841,7 +840,7 @@ TILE:    urand_alchemist
 TILE_EQ: turban_purple
 FIRE:    1
 COLD:    1
-MAGIC:   30
+MAGIC:   1
 BOOL:    elec
 
 NAME:    fencer's gloves
@@ -881,7 +880,7 @@ COLOUR:   ETC_GOLD
 TILE:     urand_gong
 TILE_EQ:  shield_gong
 EV:       -5
-MAGIC:    50
+MAGIC:    1
 BOOL:     elec, life
 
 NAME:    amulet of the Air
@@ -912,7 +911,7 @@ OBJ:     OBJ_JEWELLERY/AMU_CLARITY
 COLOUR:  ETC_POISON
 TILE:    urand_four_winds
 BOOL:    life
-MAGIC:   100
+MAGIC:   3
 
 NAME:    necklace of Bloodlust
 OBJ:     OBJ_JEWELLERY/AMU_RAGE
@@ -920,7 +919,7 @@ COLOUR:  ETC_BLOOD
 TILE:    urand_bloodlust
 STR:     2
 INT:     -2
-MAGIC:   30
+MAGIC:   1
 ANGRY:   9
 DAM:     5
 CURSED:  3
@@ -943,7 +942,7 @@ OBJ:     OBJ_JEWELLERY/RING_WIZARDRY
 COLOUR:  ETC_ENCHANT
 TILE:    urand_mage
 INT:     3
-MAGIC:   50
+MAGIC:   2
 
 NAME:     brooch of Shielding
 OBJ:      OBJ_JEWELLERY/AMU_WARDING
@@ -970,7 +969,7 @@ TILE_EQ:  wizard_bluegreen
 BRAND:    SPARM_PONDEROUSNESS
 INT:      +5
 MP:       +10
-MAGIC:    30
+MAGIC:    1
 
 ENUM:     DEMON_AXE
 NAME:     obsidian axe
@@ -1134,7 +1133,7 @@ PLUS:     +3/+6
 COLOUR:   ETC_ENCHANT
 TILE:     urand_spellbinder
 TILE_EQ:  spellbinder
-MAGIC:    30
+MAGIC:    1
 BOOL:     evil
 
 NAME:    lajatang of Order
@@ -1176,7 +1175,7 @@ DEX:     3
 EV:      3
 FIRE:    3
 INT:     3
-MAGIC:   100
+MAGIC:   3
 METAB:   10
 HP:      10
 MP:      10