If you are interested, I coded up a simulator to run multiple iterations to determine the number of "blows" actually needed to land a wound against an Extremely hard to kill model. I came up with the following:
KEY:
Number of Existing Counters (EC)
% of Killing the Model Outright (%K)
% of Getting +0 Additional Counters (%0)
% of Getting +1 Additional Counters (%1)
% of Getting +2 Additional Counters (%2)
% of Getting +3 Additional Counters (%3)
% of Getting +4 Additional Counters (%4)
% of Getting +5 Additional Counters (%5)
% of Getting +6 Additional Counters (%6)
Probability of Results
Quote:
EC _ _ %K _ _ _ _ %0 _ _ _ _ %1_ _ _ _ %2 _ _ _ _ %3 _ _ _ %4 _ _ _ _ %5 _ _ _ _ %6 _ _
00 _ 000.00% _ 050.00% _ 041.67% _ 008.33% _ 000.00% _ 000.00% _ 000.00% _ 000.00%
01 _ 000.00% _ 033.33% _ 052.78% _ 011.11% _ 002.78% _ 000.00% _ 000.00% _ 000.00%
02 _ 000.00% _ 016.67% _ 066.67% _ 000.00% _ 011.11% _ 005.56% _ 000.00% _ 000.00%
03 _ 000.00% _ 000.00% _ 066.67% _ 016.67% _ 008.33% _ 008.33% _ 000.00% _ 000.00%
04 _ 000.00% _ 000.00% _ 050.00% _ 033.33% _ 005.56% _ 008.33% _ 002.78% _ 000.00%
05 _ 000.00% _ 000.00% _ 033.33% _ 050.00% _ 002.78% _ 008.33% _ 005.56% _ 000.00%
06 _ 002.78% _ 000.00% _ 016.67% _ 066.67% _ 000.00% _ 000.00% _ 005.56% _ 008.33%
07 _ 005.56% _ 000.00% _ 000.00% _ 066.67% _ 016.67% _ 000.00% _ 002.78% _ 008.33%
08 _ 008.33% _ 000.00% _ 000.00% _ 050.00% _ 033.33% _ 000.00% _ 000.00% _ 008.33%
09 _ 016.67% _ 000.00% _ 000.00% _ 033.33% _ 050.00% _ 000.00% _ 000.00% _ 000.00%
10 _ 033.33% _ 000.00% _ 000.00% _ 016.67% _ 050.00% _ 000.00% _ 000.00% _ 000.00%
11 _ 050.00% _ 000.00% _ 000.00% _ 000.00% _ 050.00% _ 000.00% _ 000.00% _ 000.00%
12 _ 066.67% _ 000.00% _ 000.00% _ 000.00% _ 033.33% _ 000.00% _ 000.00% _ 000.00%
13 _ 083.33% _ 000.00% _ 000.00% _ 000.00% _ 016.67% _ 000.00% _ 000.00% _ 000.00%
14 _ 100.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00%
15 _ 100.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00%
16 _ 100.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00% _ 000.00%
After many runs of the dice rolls, I came up with an Average number of Hits as being 9.5, with the most probable outcome being 10 Hits to kill.
The simulator did provide a couple "interesting" results where it killed the monster in 3 Hits and another where it killed the monster in 17 Hits:
Three Hit Example:
It rolled a 6/3 (giving 2 counters on the First Hit), followed by a 6/5 (giving 4 counters on the Second Hit), followed by a 6/6 (producing the 15 required to kill the monster)! That was pretty interesting.
Seventeen Hit Example:
It rolled a 2 (giving 0 counters on the First Hit), followed by a 3 (giving 0 counters on the Second Hit), follwed by another 3 (giving 0 counters on the Third Hit), then another 3 (giving 0 counters on the Fourth Hit) ... there was this enormous string of 1's, 2's and 3's ... which made each Hit "invalid").