Back in the early days of my Summoner Wars career, I posted a thread where I listed all of the odds for making standard 1, 2, 3, 4, and 5 AV attacks:

http://www.plaidhatgames.com/sum_forums/showthread.php?1901-Never-Tell-Me-The-Odds-Summoner-Wars-Math-Made-Easy&p=78480#post78480

Forum user kaszkiet made an awesome reference card that you can print out at home with all of these percentages:

Never Tell Me the Odds Reference Card

 

 

If you'd like to print this, here it is in high resolution.  I've rescaled the front and back to be the same size as Summoner Wars cards (58mm x 88mm) if you print it at 300 DPI.

 

Never Tell Me the Odds Reference Card Front

Never Tell Me the Odds Reference Card

Update: Forum user Lets play a game has provided this chart with even more details:

Lots of Dice Probabilities

If you'd like to use a handy calculator for Units like Mook-backed Cave Goblins or Blagog, the following site found by Joepinion is also quite useful:

http://stattrek.com/online-calculator/binomial.aspx

Probability of success - Enter (as a decimal) the probability of getting a Hit on 1 die.  For example, hitting on a 3+ (normal AV) would give you .666667.  Hitting on a 6+ would give you .1666667.  Hitting a Mook-backed die (2+) would give you .833333333.

Number of trials - Enter how many dice you’re rolling

Number of successes (x) - Enter how many Hits you need

Outputs:

Binomial probability: P(X = x) - The probability of getting exactly how many hits you need

Cumulative probability: P(X < x) - The total probability of getting fewer Hits than you need (can be quite useful)

Cumulative probability: P(X < x) - The total probability of getting fewer or as many Hits as you need (not very useful)

Cumulative probability: P(X > x) - The total probability of getting more Hits than you need (not very useful)

Cumulative probability: P(X > x) - The total probability of getting as many or more Hits than you need (the most useful number, typically)