The Goblin Gang will be unlocked starting at Arena 8.
The Goblin Gang is literally the combination of Goblins + Spear Goblins.
When deployed, it will always spawn three Goblins in the front while the other 3 Spear Goblins will spawn at the back.
This card will save you 1 Elixir as oppose to deploying the two cards separately.
The Goblin Gang (120) runs slightly faster than the Skeleton Army (90) which means that they will reach their target a lot faster than the popular Skarmy. More importantly, the Goblins will survive a direct hit from a max level zap. One of the biggest strengths of this card, over Skarmy, is that the Goblins do not melt instantly from the Poison spell. With the recent buff of the Poison spell that literally hard counters the Skeleton Army and Graveyard, Goblin Gang may be a good alternative to the popular card for your Spawner deck.
More importantly, since the Goblin Gang is the first card in the game that spawns both Melee and Range troops, this card is surprisingly amazing when dealing with Splash units (e.g. Valkyrie). Lastly, this card can help you deal against Minion Horde quite easily.
Whilst the new card may be enticing for most Spawner decks, keep in mind that Skarmy is still as viable as it once was since this card generally outnumbers the Goblin Gang’s sheer count. This means that Skeleton Army will outperform the former when it comes to total DPS. The main problem, however, is that both of them are highly susceptible to spells such as The Log for a positive Elixir trade.
When it comes to taking down Giants and other tanks, Skeleton Army still takes out these troops a lot faster than the Goblin Gang. And so, you might consider this factor when facing against Golem decks. Lastly, the Skeleton Army will be much more effective against the Executioner in the upcoming balance update in which, Supercell will fix the troop’s numerous bugs.
Overall, when it comes to choosing between the two cards, it all boils down to the type of deck that you are facing. Goblin Gang would be much more effective against decks that have Minion Horde and/or Ground Splash units such as the Electro-Wizard or Valkyrie. Meanwhile, Skeleton Army excels at taking down heavy tanks in the game.