Level 1. RUG, ERA, AGE, URGE, ARGUE, RAGE
Level 2. TARE, TEAR, RATE, TALE, LATER, ALTER, ALERT
Level 3. TIN, TIE, NET, TEN, VINE, INVITE, VET
Level 4. CUT, TUB, CUE, BUT, CUTE, BUCKET, BET
Level 5. LOW, WOOL, WOLF, FLOW, FOLLOW, WOO
Level 6. DIE, DICE, DEED, DECIDE, ICE
Level 7. PER, FEE, REEF, PEER, PREFER, FREE
Level 8. END, VINE, DINE, DIVE, DIVINE, VEIN
