Crit Hits Large and Super Large Creatures

Criticals against Large and Super-Large Creatures
Certain unusual creatures are so large and/or powerful that the normal critical strike tables are not used when they receive critical strikes. Unusual creatures are separated into two categories:

Large Creatures (Trolls, Giants, Demons, and Undead, etc.).
Super-Large Creatures (Dragons, very powerful Demons, etc.).
Each category has its own critical strike table that is consulted if a sufficiently severe critical strike is obtained against them. The roll for criticals against Large and Super-Large creatures is high open-ended.

LARGE CREATURE CRITICAL STRIKES
Only critical strikes of severity ‘B’, ‘C’, ‘D’, or ‘E’ affect large creatures (i.e., ‘A’ severity criticals are ignored). A high open-ended roll is made and cross-indexed with the weapon type on the Large Creature Critical Strike Table (4.4). The result obtained is applied immediately.
Note that the severity of the critical strike is irrelevant, except that it must be of ‘B’ severity or higher. This reflects the fact that such creatures present such a large target that they are much more difficult to seriously hurt.

SUPER-LARGE CREATURE CRITICAL STRIKES
Only critical strikes of severity ‘D’ or ‘E’ affect super-large creatures (i.e., ‘A’, ‘B’, and ‘C’ severity criticals are ignored). A high open-ended roll is made and cross-indexed with the weapon type on the Super-Large Creature Critical Strike Table (4.10). The result obtained is applied immediately.
This table should be consulted of only for creatures such as Dragons, Dinosaurs, and the most powerful Demons.

High Open-ended Roll — To obtain a “high open-ended roll” first make a 1-100 roll. A roll of 96-00 indicates a particularly fortunate occurrence for the roller. The dice are rolled again and the result is added to the first roll. If the second roll is 96-00, then a third roll is made and added, and so on until a non 96-00 roll is made. The total sum of these rolls is the result of the high open-ended roll.
Example: The GM asks a player to make a high open-ended roll, and the initial roll is a 99. A second roll is made with a result of 96; so a third roll is made with a result 04. Thus, the high open-ended roll that the GM requested is 199 (= 99 + 96 + 04).