I think your a little off...
It only takes 3 landslides.
At 3 landslides, there are no open slots left (there are only 5 non-flooded slots in the central row).
Further, the enemy player has had their creature pushed into a flooded slot, where it will likely die.
lets label the slots
flooded | * | * | * | * | * | flooded
| 5 | 3 | 1 | 2 | 4 |
1st landslide: enemy creature gets pushed left, new boulder in central slot. slots 1&2 filled
2nd landslide: enemy gets pushed left again, boulder in center gets pushed right. slots 1,2,3,4 filled
3rd landslide: enemy creature gets pushed to flooded slot on right, boulders now fill slots 1,2,3,4,5
So this takes:
3 landslides
1 BB, or plate armor (if enemy creature has 3 or fewer HP)
Opponent only needs to play a single creature.
This is a 4 card combo if the opponent plays a creature with more than 3 HP.
-Flooding, 3 of this
Breaking the lock isn't that easy either.
PC works, but PA can thwart that
CC works, but there are few Mass CC spells that can take out a 0|5 boulder on the player's own side, so they would have to waste valueable CC spells on clearing their field... Even with lightening bolts, you will rebuild 2 boulders with a single landslide while they can only cut down 1 per bolt.