diff --git a/src/cryp.rs b/src/cryp.rs
index d05b5314..fc64349c 100755
--- a/src/cryp.rs
+++ b/src/cryp.rs
@@ -1,22 +1,66 @@
 use uuid::Uuid;
 use rand::prelude::*;
 
+#[derive(Debug,Clone,Copy,PartialEq)]
+pub enum StatKind {
+  Dmg,
+  Def,
+  Hp,
+  Stam,
+}
+
+#[derive(Debug,Clone)]
+pub struct Mod {
+  pub name: String,
+  pub value: u64,
+  pub affects: Vec<StatKind>,
+}
+
+#[derive(Debug,Clone)]
 pub struct Roll {
   pub roll: u64,
   pub result: u64,
-  // pub stat: Stat,
+  pub kind: StatKind,
 }
 
 #[derive(Debug,Clone)]
 pub struct Stat {
-  value: u64,
+  pub value: u64,
+  pub kind: StatKind,
 }
 
 impl Stat {
-  fn roll(&self) -> Roll {
+  fn set(&mut self, v: u64) -> &Stat {
+    self.value = v;
+    self
+  }
+
+  fn roll(&self, c: &Cryp) -> Roll {
     let mut rng = thread_rng();
     let roll: u64 = rng.gen();
-    return Roll { roll, result: self.value & roll };
+
+    println!("{:?}", self.kind);
+    println!("{:064b}   <- base roll", roll);
+
+    let active_mods = c.mods.iter().filter(|m|
+      m.affects.iter().any(|a| *a == self.kind)
+    ).collect::<Vec<&Mod>>();
+
+    // println!("{:?}", active_mods);
+    let mod_roll = active_mods.iter().fold(roll, |roll, m| {
+      let roll_with_mod = roll | m.value;
+      println!("{:064b} | <- {:?}", m.value, m.name);
+      roll_with_mod
+    });
+
+    println!("{:064b}   <- modified roll", mod_roll);
+
+    let result = self.value & mod_roll;
+    println!("{:064b} & <- attribute roll", self.value);
+    println!("{:064b} = {:?}", result, result);
+    println!("");
+
+    return Roll { kind: self.kind, roll, result };
   }
 
   fn reduce(&mut self, dmg: u64) -> &mut Stat {
@@ -25,14 +69,6 @@ impl Stat {
   }
 }
 
-fn print_roll(r: &Roll) {
-  // println!("{:?}", r.att);
-  println!("{:064b} &", r.roll);
-  // println!("{:064b}", r.value);
-  println!("{:064b} - {:?}", r.result, r.result);
-  println!("");
-}
-
 pub struct Turn {
   pub dmg: Roll,
   pub def: Roll,
@@ -49,6 +85,7 @@ pub struct Cryp {
   pub hp: Stat,
   pub xp: u64,
   pub lvl: u8,
+  pub mods: Vec<Mod>,
   pub name: String,
 }
 
@@ -62,12 +99,13 @@ impl Cryp {
     let id = Uuid::new_v4();
     return Cryp {
       id,
-      dmg: Stat { value: 0},
-      def: Stat { value: 0},
-      stam: Stat { value: 0},
-      hp: Stat { value: 0},
+      dmg: Stat { value: 0, kind: StatKind::Dmg },
+      def: Stat { value: 0, kind: StatKind::Def },
+      stam: Stat { value: 0, kind: StatKind::Stam },
+      hp: Stat { value: 0, kind: StatKind::Hp },
       lvl: 0,
       xp: 0,
+      mods: vec![],
       name: String::new()
     };
   }
@@ -82,6 +120,11 @@ impl Cryp {
     self
   }
 
+  pub fn add_mod(&mut self, m: Mod) -> &mut Cryp {
+    self.mods.push(m);
+    self
+  }
+
   pub fn add_xp(mut self) -> Cryp {
     self.xp = self.xp.saturating_add(1);
     if self.xp.is_power_of_two() {
@@ -97,11 +140,8 @@ impl Cryp {
 
   pub fn turn(&self) -> Turn {
     // println!("{:?}'s turn:", c.name);
-    let dmg = self.dmg.roll();
-    let def = self.def.roll();
-
-    print_roll(&dmg);
-    print_roll(&def);
+    let dmg = self.dmg.roll(self);
+    let def = self.def.roll(self);
 
     return Turn { dmg, def }
   }
@@ -116,10 +156,10 @@ impl Cryp {
 
     self.xp = lvl_as_two_pwr;
 
-    self.dmg = Stat { value: rng.gen_range(1, max) };
-    self.def = Stat { value: rng.gen_range(1, max) };
-    self.stam = Stat { value: rng.gen_range(1, max) };
-    self.hp = Stat { value: self.stam.value };
+    self.dmg.set(rng.gen_range(1, max));
+    self.def.set(rng.gen_range(1, max));
+    self.stam.set(rng.gen_range(1, max));
+    self.hp.set(self.stam.value);
     self
   }
 
@@ -148,17 +188,26 @@ impl Cryp {
 
 #[cfg(test)]
 mod tests {
+  use cryp::{StatKind,Mod};
   use *;
 
   #[test]
   fn create_cryp_test() {
-    let level_two = Cryp::new()
+    let newborn = Mod {
+      name: "newborn".to_string(),
+      value: 0,
+      affects: vec![StatKind::Def],
+    };
+
+    let mut level_two = Cryp::new()
       .named("hatchling".to_string())
       .level(2)
       .create();
+
+    level_two.add_mod(newborn);
     // assert!(level_two.dmg <= 2_u64.pow(2));
     // assert!(level_two.def <= 2_u64.pow(2));
-    // assert!(level_two.stam < 2_u64.pow(2));
+    assert_eq!(level_two.mods.len(), 1);
     println!("{:?}", level_two);
     return;
   }
diff --git a/src/lib.rs b/src/lib.rs
index 6eb2d88a..49d22f0f 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,14 +7,22 @@ mod battle;
 
 use combat::{battle, levelling};
 use battle::{Battle};
-use cryp::Cryp;
+use cryp::{Cryp, Mod, StatKind};
 
 pub fn main() {
-  let a = Cryp::new()
+  let mut a = Cryp::new()
     .named("pronounced \"creeep\"".to_string())
     .level(8)
     .create();
 
+  let stoney = Mod {
+    name: "stoney".to_string(),
+    value: 127,
+    affects: vec![StatKind::Def],
+  };
+
+  a.add_mod(stoney);
+
   let b = Cryp::new()
     .named("lemongrass tea".to_string())
     .level(8)