Mimic

Mimic is a safe-zone and you will not lose items upon death.

Preparation

Mimic has a combat level of 999 and spawns 3 hours after he is killed, so has a the potential to be killed 8 times a day.
His total hit-points is determined by the number of players online when he spawns.
Mimic is a tough fight and is recommended to have at least a group of 2 players.

He is found a few steps south of home and can be accessed using the ::mimic teleport command. Click the portal at the bottom of the path leading up to the Colosseum the enter the arena.
Get your best ranged gear and fill your inventory with an Overload/ Combat potions, Super restores/ Prayer potions, Purple sweets if you have them, then fill the rest with your best food.
You can use a looting bag for more inventory space.

You can exit the arena via the Blue Portal or tele out.

The fight

Mimic has 4 different projectile attacks each represented by a different color of candy. Prayer flicking is possible but you have to be fast or you will take damage.
Green candy, use protect from range.
Blue candy, use protect from magic.
Red candy, use protect from melee.
Purple candy, is his special attack hits through prayer and deals 30 damage 100% of the time.
He does have an additional melee attack if you're in close distance, which can turn off your prayers.

The general strategy is to stand back, use ranged attacks, and pray flick to the best of your ability. You WILL take lots of heavy hits so be ready to heal up quick.
There is a minimum damage requirement of 200hp in order to receive loot. If you leave the arena to get more food, or you die, this will be reset. So time this wisely so you don't miss out on the loot.

Mimic performing a magic attack.

Rewards

Crystal of trahaearn
Druidic wreath
3rd age druidic top
3rd age druidic bottoms
3rd age druidic cloak
3rd age druidic staff
3rd age wand
3rd age bow
3rd age bow
Scythe of Chaos

Note, the constant 5M gp drop can stack with the other coin drops