The buff from 2 to 3 damage on Holy smite makes the puzzle lab Three Odd Yetis undoable as you were supposed to deal 2 damage to the crocolisk on the right, and now you kill it.
That puzzle was not changed because it is still solvable.
It’s the last puzzle of the block, so it’s supposed to be a bit harder. Try to consider all possible actions you have with the minions, cards, and hero power.
PS: Here’s a screenshot I just took, after trying the puzzle to ensure my claim is right: https://imgur.com/a/T0keB7D
PS 2: I see Rhasimir just spoon-fed you the solution… I hope they didn’t spoil too much of the fun for you.
There were two solutions to that puzzle originally. The other solution does not care whether Holy Smite does 2 or 3 damage, so the puzzle is still solvable.
I have personally answered this exact question many times. If you don’t want to figure the puzzle out and prefer a solution be given to you, here it is (courtesy Gamepedia):
- Attack the undamaged enemy [Chillwind Yeti] with the left-most [River Crocolisk]
- Attack the enemy River Crocolisk with the remaining River Crocolisk
- Use the Hero Power [Lesser Heal] on the right-most enemy Yeti
- Cast [Holy Smite] on the friendly River Crocolisk