feat: add ring of concentration

data/des/des-main.des

@@ -708,4 +708,8 @@ $cDuration:$. Ring duration lasts for $bwillpower$. turns.
 
 % condemnation
 $cEffect:$. Destroys a single undead enemy, at the cost of $b20 - willpower$.
-turns of Held.
+turns of $aHeld$..
+
+% concentration
+$cEffect:$. Doubles your willpower for $bwillpower * 2$. turns, at the cost of
+$aSlow$., $b-100 Melee%$., and $b-100 Evade%$. for the same duration.

data/des/des-statuses-nonplayer.des

@@ -19,6 +19,9 @@ This is supposed to be a player-only status, and is probably a bug.
 % nonplayer_Status.RingDeception
 This is supposed to be a player-only status, and is probably a bug.
 
+% nonplayer_Status.RingConcentration
+This is supposed to be a player-only status, and is probably a bug.
+
 % nonplayer_Status.DetectHeat
 This is supposed to be a player-only status, and is probably a bug.
 

data/des/des-statuses-player.des

@@ -19,6 +19,9 @@ Refer to the ring's description.
 % player_Status.RingDeception
 Refer to the ring's description.
 
+% player_Status.RingConcentration
+Refer to the ring's description.
+
 % player_Status.DetectHeat
 You are detecting sources of heat, as well as enemies attuned to fire.
 

data/status_help.tsv

@@ -8,6 +8,7 @@
 .RingConjuration   	"ring: conjuration"   	 "house of pain"       	 -
 .RingAcceleration  	"ring: acceleration"  	 "is in effect"        	 -
 .RingDeception     	"ring: deception"     	 "voting for trump"    	 -
+.RingConcentration 	"ring: concentration" 	 "using the Force"     	 -
 .DetectHeat        	"detect heat"         	 -                     	 -
 .DetectElec        	"detect electricity"  	 -                     	 -
 .EtherealShield    	"ethereal shield"     	 -                     	 -

src/items.zig

@@ -213,6 +213,7 @@ pub const RINGS = [_]ItemTemplate{
     .{ .w = 9, .i = .{ .r = DetonationRing } },
     .{ .w = 9, .i = .{ .r = DeceptionRing } },
     .{ .w = 9, .i = .{ .r = CondemnationRing } },
+    .{ .w = 9, .i = .{ .r = ConcentrationRing } },
 };
 pub const NIGHT_RINGS = [_]ItemTemplate{
     .{ .w = 9, .i = .{ .r = ExcisionRing } },
@@ -1014,6 +1015,25 @@ pub const CondemnationRing = Ring{ // {{{
     }.f,
 }; // }}}
 
+pub const ConcentrationRing = Ring{ // {{{
+    .name = "concentration",
+    .required_MP = 1,
+    .stats = .{ .Willpower = 1 },
+    .requires_nopain = true,
+    .effect = struct {
+        pub fn f() bool {
+            const will = @intCast(usize, state.player.stat(.Willpower));
+            const duration = math.max(1, will * 2);
+            state.player.addStatus(.RingConcentration, 0, .{ .Tmp = duration });
+            state.player.addStatus(.Slow, 0, .{ .Tmp = duration });
+
+            state.message(.Info, "Your consciousness begins withdrawing from your physical body.", .{});
+
+            return true;
+        }
+    }.f,
+}; // }}}
+
 pub const ExcisionRing = Ring{ // {{{
     .name = "excision",
     .required_MP = 5,

src/player.zig

@@ -937,12 +937,14 @@ pub const RingError = enum {
     NotEnoughMP,
     HatedByNight,
     CannotBeCorrupted,
+    CannotBeInPain,
 
     pub fn text1(self: @This()) []const u8 {
         return switch (self) {
             .NotEnoughMP => "low mana",
             .HatedByNight => "hated by the Night",
             .CannotBeCorrupted => "must be uncorrupted",
+            .CannotBeInPain => "must not be in pain",
         };
     }
 };
@@ -958,6 +960,9 @@ pub fn checkRing(index: usize) ?RingError {
     if (ring.requires_uncorrupt and state.player.hasStatus(.Corruption)) {
         return .CannotBeCorrupted;
     }
+    if (ring.requires_nopain and state.player.hasStatus(.Pain)) {
+        return .CannotBeInPain;
+    }
     return null;
 }
 

src/types.zig

@@ -1129,6 +1129,7 @@ pub const Status = enum {
     RingConjuration, // No power field
     RingAcceleration, // No power field
     RingDeception, // No power field
+    RingConcentration, // No power field
 
     // Item-specific effects.
     DetectHeat, // Doesn't have a power field.
@@ -4090,6 +4091,14 @@ pub const Mob = struct { // {{{
                         val = @divTrunc(val * 50, 100);
                     };
             },
+            .Melee => {
+                if (self.hasStatus(.RingConcentration))
+                    val -= 100;
+            },
+            .Evade => {
+                if (self.hasStatus(.RingConcentration))
+                    val -= 100;
+            },
             else => {},
         }
 
@@ -4705,6 +4714,7 @@ pub const Ring = struct {
     stats: enums.EnumFieldStruct(Stat, isize, 0) = .{},
     hated_by_nc: bool = false,
     requires_uncorrupt: bool = false,
+    requires_nopain: bool = false,
     effect: fn () bool,
 };