Learn how to prep crit and bash in Dota 2 with PRNG

Learning how to prep crit and bash is a core skill in Dota 2, so it’s a surprise how few players actually do it.

Random number generation is generally considered uncompetitive at best and game-ruining at worst. However, the concept is also baked into the core of Dota 2. Many abilities and spells use RNG to determine their effects, with some heroes practically built around luck, such as Chaos Knight, Phantom Assassin, and Ogre Magi. Luckily for players, not everything is quite as random as it seems. Here’s a brief explanation of how PRNG works in Dota 2 and how to use it to prep bash and crit. 

First, it’s important to clarify how Dota 2 handles percentage-based chances. The majority of chance-based item abilities, such as Daedalus crit or Skull Basher bash, use something called pseudo-random number generation to determine if they activate or not. PRNG, as it’s known, balances these effects by changing their likelihood of proccing as the character continues to attack. This is why bashing someone five times in a row is so rare. The chance to bash gets massively reduced for attack after the initial bash.

As an example, Chaos Knight’s odds to crit with Chaos Strike is listed as 33%. However, it’s uncommon to get two crits consecutively. This is because the odds drastically lower right after Chaos Strike procs, and additional hits are needed to bring it up to 33%. If you miss Chaos Strike three times in a row, however, the odds of hitting it on the fourth attack actually go above 33%.

PRNG also controls evasion in Dota 2, which is why Phantom Assassin tends to get hit by every other attack instead of streaking misses and hits. When an attack is dodged, her chance of avoiding the next attack is lowered to 25%. It becomes 50% upon being hit once, then goes up to 75% if the attack lands successfully. The goal of PRNG is to standardize RNG elements so that they happen more consistently. This helps make the RNG element much more competition-friendly.

How to use PRNG to prep crit and bash in Dota 2

If you plan to play PRNG-reliant heroes in Dota 2, learning how to prep effects like crit and bash is crucial.

Back to the Phantom Assassin example, Coup de Grace only has a 15% chance of activating. However, the chance is actually much lower for the first attack after a crit. Luckily, the game keeps tracking this chance across multiple targets. That means that if you attack creeps five times and do not get a Coup de Grace crit, you are very likely to hit one when you Phantom Rush the next target.

The exact number of attacks to prep a bash or crit depends on the chance of it happening. For Spirit Breaker, he has a slightly higher chance of proccing Greater Bash at 17%, so four hits may be optimal. Juggernaut’s Blade Dance is much more common at 35%, so just two hits are needed to prep. It’s also possible to prep beyond the average number of hits needed to proc, which is less reliable but can nearly guarantee effects on the next attack.