Elemental Fear

[Shiva_]

If you see one, always turn gambits OFF so a spell won't get cast at all. Your buffs are often automatically recast while you're walking and not fighting, and you don't want this to happen if you see an Elemental or Entite.

If you end up making one hostile, equip everyone with Nishijin Belts right away as they protect from sleep. Then, flee.

With those Entites, Sleepga is what will really get you in trouble as Entites use only magic, and attack magic doesn't wake up your characters (the only time where you may get woken up is if surrounding mobs physically attack you, but don't count on that). Entites, Elementals, and other magical creatures often ignore magic evade so their status spells will always hit at a 100% rate unless you have an accessory that makes you IMMUNE to a given one.
Silencega isn't as bad because you are still mobile, and once you're in another section and out of the Entite's sight, you can then take care of the silence status with something like Self > Echo Herb gambits and/or Esuna.

If you want to try to take on Entites at lower levels (e.g. for purposes of farming for Feystones and stealing Halcyons for ingredients for certain powerful weapons, filling bestiary, etc):
1) Make sure everybody has Nishijin Belts on. This makes it so his Sleepga doesn't effect you.
2) Keep Bubble up on everybody at all times using the Bubble spell.
3) Have Self > Echo Herb gambits to get rid of silence status quickly anytime he uses his Silencega spell.
4) Be prepared to use Charge anytime he uses Fear (this drains your MP). Depending on where you are in the game, you may have a Self: MP<10% gambit you can use for Charge. If you don't have this yet, just use Charge manually. 5) Keep everyone Shell'ed to reduce damage from his elemental magic attacks. The Shell Shield can be useful for an ally as it gives Auto-Shell.
6) Most importantly, know how to defend against elemental attacks by using the proper armor/helmet/shield/accessory to resist/immunize against a given element or to absorb damage from it.