Clash of zones killing event: if I teleport to enemy state can I use the shield?

You cannot attack players (or scout them) with a shield active. You can teleport to the enemy state but you must drop the shield to attack. Once your shield drops you can then move around after attacking to try to avoid being hit back or just fight your attackers. (higher level bases though it is best to run away from).

Note: when your shield drops you will have to wait 1 minute for every level of your base (level 20 = 20 minutes timeout) before you can apply another shield. This is to stop players doing as you said and hitting groups and re-shielding immediately. When you are done you can teleport back to your own state to your original location or any other). You need to have an advanced teleport item for every jump you make though so make sure you have enough saved up or purchase some more with diamonds or alliance points.