I have found out the best way by far to train slayer in this server is to train at soulwars. To get here type command ::soulwars.
If you get at least 1 kill within the time limit you receive 8 zeals...If you do not manage to get at least 1 kill you will receive 1 zeal.
Trade Nomad to recieve exp in slayer...It's 130k (130,000) exp per 2 zeal.
Hope this helped out =]
