In order to get past this level, you need to solve the riddles with the answers being SAND and FISH. Then you should transform them in the following ways:
SAND -> HAND -> HAN -> TAN
FISH -> FIST
This second part becomes more difficult. You should start with the source words: STRAIN, STRIFE, PAST
You will then need to transform them in the following ways:
STRAIN -> TRAIN -> TREEN -> EENRT -> EENR -> EEN -> OWN -> NOW
STRAIN -> TRAIN -> TREEN -> TREE
STRIFE -> STRIF -> FIRST -> FIRS -> FIR
PAST -> PAT -> NAT -> ANT
(Bolded words are used to unlock gates.)
The source words are: SOVEREIGN, SEA, TEN, DIME, STUMBLE, ABBEY, SLATE
Here are the suggested transformations:
SOVEREIGN -> SOVERE -> RESOVE -> ROSEVO -> ROSE -> ROZE -> ZERO
SEA -> SEEAA -> SE -> SEE -> SOO -> ZOO
DIME -> PENNY -> PEONY
TEN -> ONE -> OONEE -> OONE -> PONE -> ONEP -> HONEP -> PHONE
STUMBLE -> UMBLEST -> UMBLE -> HUMBLE
ABBEY -> ACBEY -> ACBE -> BEAC -> HBEAC -> BEACH
SLATE -> ATESL -> ATE -> AATEE -> ATEEA -> ATFEA -> ATFE -> FEAT
(Bolded words are gate keys.)