Stay 45 def, and train the skills as if he were a main.
These are called rune / zerker pures.
Very effective in mid / high crater + you can still have it as a main with the skills etc.
N.B when you do dragon slayer you get a lot of def XP so stay 40 when you do it.
Be A zerker main... Get 30 def 60 atk 60 str 60 range 60 mage and do monkey madness and dragon slayer after that get your def to 45 but before the quest you must have 30 def or your def will go higher... Then go get all your stats 30+ with 1 - 3 stats 70+ i'd do fletch wc and fishing for money.
Better method for rune pure, cuz if you do what they say, you'll end up with 46-48 def, which SUCKS for a rune pure. Do D slayer with LOW def, 30 tops, then do FREMMY TRIALS, it gives def exp, and then do parts of RFD, one part gives 2K def exp, and presto, 45 def with addy/rune gloves, get 70 att 99 str, and bam, gud rune pure.