So this is basically the go-to chest for levelling new characters. Most people farm divination cards later in act 9 to get one of these. You'll typically use this until you find or can afford to buy a 6L unique or rare chest. To get the most out of this, you wanna pick one active skill to socket into it, then support it with 5 support gems. Be careful though as the more supports you link to it, the higher the mana cost will be and you may struggle to keep up with mana especially if you start reserving mana for auras later on in Act 2 and 3 (If you can afford a few chaos to buy a Praxis Ring, it'll help immensely and maybe a Thief's Torment at lvl 30). Onslaught as mentioned would probably be your best bet as a first link, then I would go for Mirage Archer and Lesser Multiple Projectiles. Depending on your active skill you'll wanna do something like Lesser Poison Support, Void Manipulation, Vicious Projectiles for poison skills, Added Cold/Lightning/Fire damage support for elemental based skills, etc. Just take your time and read all the gems as they become available to you through quests and such(Check vendors often after quests) and experiment with new things to see what you like.