Here is a very simple chart for throwing a curve to the monsters / foes in DnD that your party will face.
Roll D4 - 1 for number of changes for each group of monsters/foes encountered. Then roll a D12 on the chart below for each change.
1) Increased HD (1-2)
2) Attack more damaging (one die up)
3) New Magical ability (per spell of HD - 3, min level 1 mage or cleric power)
4) Additional Feat or feat like power
5) Increased (better AC)
6) Additional Attack
7) Increased number of appearing
8) Unlikely ally monster(s) of 1-2 less 3-4 equal or 5-6 greater strength
9) Alignment / motivation change (sometimes beneficial)
10) Reinforcements near by
11) Treasure type increased by one letter (or equivalent)
12) Monsters / Foe more cunning that usual (ambush, traps, delays)
Roll D4 - 1 for number of changes for each group of monsters/foes encountered. Then roll a D12 on the chart below for each change.
1) Increased HD (1-2)
2) Attack more damaging (one die up)
3) New Magical ability (per spell of HD - 3, min level 1 mage or cleric power)
4) Additional Feat or feat like power
5) Increased (better AC)
6) Additional Attack
7) Increased number of appearing
8) Unlikely ally monster(s) of 1-2 less 3-4 equal or 5-6 greater strength
9) Alignment / motivation change (sometimes beneficial)
10) Reinforcements near by
11) Treasure type increased by one letter (or equivalent)
12) Monsters / Foe more cunning that usual (ambush, traps, delays)
Comments