2019-08-23 : If a cost contains a mana symbol that may be paid in multiple ways, such as {B/R}, {B/P}, or {2/B}, you choose how you’ll pay it before you do so. If you choose to pay {B} this way, K’rrik’s ability allows you to pay life rather than pay that mana.

2019-08-23 : K’rrik’s ability doesn’t modify or reduce costs you pay. It changes only how you may pay those costs.

2019-08-23 : K’rrik’s ability lets you pay 2 life for {B} in any cost you pay, including casting costs, activation costs, and even costs for special actions (such as morph). Any time you pay mana, that’s a cost.

2019-08-23 : K’rrik’s last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.

2019-08-23 : You can’t pay 2 life to pay for generic mana in costs you pay, even if an effect says that you must spend black mana to pay that generic mana.