Stasis Giant is a sub-boss found on the 180th floor of Tartarus in a group of three. They impede the party's progress and must be beaten to proceed. It later reappears as a normal enemy in the Harabah Block, between floors 202 to 213.
Try to bring any high level +Evade Slash shoes equipped with the protagonist and a Persona with both healing skills and multi-target Ice/Elec skills (Titania for example). Party can consist of anyone except Aigis, Junpei or Koromaru due to the boss resisting both Fire and Physical attacks. One's best bet would be to go with someone who has a healing skill of their own (Ken, Akihiko, Mitsuru and Yukari) and someone who has a multi-target Ice/Elec ability (Mitsuru and Akihiko). Chernobog is an incredibly useful Persona for this fight, because while he may not inherently have any particularly effective attacks against the Giants, he eventually learns Megido and his immunity to Slash damage can dramatically increase the protagonist's survival odds. Attack Mirrors are also very helpful for this fight, like they are in most melee-centric boss battles.
If the protagonist has shoes with high +Evade Slash and their party members were to be knocked unconcious, it is a lot safer to try and keep themself alive by using healing skills and attacking while at full health rather than wasting a turn reviving them.
Using Byakko or any other Persona with the Virus Breath skill, the protagonist may also quickly cut down their HP, and switch to elemental attacks as the percentage reduction becomes less effective. Any attackers in the group would also benefit from focusing on one giant at a time, as otherwise they would use multi-target skills and leave all three alive and give them more chances for heavily damaging attacks.
Stasis Giants will appear again in the second and third sections of Antenora within the Abyss of Time. They will generally use Matarunda before attacking. Due to their Evade Slash skill, it may be more advantageous to use Ice skills against them.
Stasis Giant appears in 6th and 7th Paradise of Heaven within the Midnight Channel. It will attack physically and cannot be dizzied. After being defeated, it may drop Prime Steel. Selling 4 Prime Steel will unlock the Kenka sword for the protagonist.
In Golden, it appears in Paradise 3 through 9 in Heaven. It may drop Sunstone for trade at Shiroku Pub.