Blast procs consist of two distinct components – the normal stun on recovering victims which is displayed by the icon and the knockdown which isn't depicted – that can stack for additionally increased damage, up to 450.36x with the procs listed above.
The damage increase from the knockdown lingers briefly longer than the one of the depicted icon.
Note that conditions or abilities that prevent knockdowns (e.g. Bastille) will hinder the second component from increasing damage.
The bonus damage is not applied to a hit which inflicted a new status effect; that means if a melee strike inflicts the first Gas status effect onto a target, then this strike's damage (including its status effect and every DoT tick until the duration ends) will not be amplified by 1.6x. Only subsequent strikes will be amplified. Therefore, if a target already dies from the first strike that inflicts a status effect then Condition Overload is not of any use; it only is if the target survives this first strike.
To achieve a high amount of distinct status procs, it is advised to use melee weapons that feature high attack speed with either high base status chance, or innate elemental status such as the Caustacyst or Twin Basolk. To achieve a high amount of distinct status procs for ranged weapons, it is advised to use weapons that feature high fire rate or AoE with innate elemental status, such as Staticor or Pox.
It's also a good idea to use it when running any Warframe that can also inflict status, such as Saryn, Ember, or Equinox.
Using in conjunction with the ArtaxSentinel weapon is recommended, since it has a guaranteed Cold proc which not only adds damage but also slows enemies down, making them easier to chase and kill. Since Sentinel weapons tend to fall off against higher-level targets, the additional damage and utility from Artax makes up for the loss in Sentinel damage.