If you have problems with an individual avatar griefing you or breaking the Linden Labs terms of service (TOS) or SL Community Standards while in Ozland then you may wish to ban them from your parcel as a first response. You should also send in an Abuse Report (AR) to Linden Labs and also inform Llola and Sven.
The best way to ban an avatar on your own land is to right click on them and select Freeze from the pie menu - this gives you 30 seconds in which they cannot move or talk - time to take a deep breath - take a snapshot for evidence - and then chose Eject and Ban from the pie menu. It is also a good idea to take a copy of the chat from just before the incident to when you Freeze them. This is also evidence that Linden Labs can use to ban someone from SL.
Freeze step 1
Freeze step 2
Eject step 1
Eject step 2
If you don't have time to Click on the offender then you can use the About Land menu to add them to a specific ban list - Note that general ban lines are not allowed in Ozland, see Sven and Llola's Tips: General Ban Lines