Dimensions End: Entropy - Tier 4. This tier has enemies Immune to Debuffs. Every wave has a single boss and the score is tight for this tier. The recommended roles are ST DPT, Battery and Debuff Evasion helps. The bosses' total HP is 5,100,000. The turn requirement is 135. The DPT you need is 36K.
Wave 1 (Boss Wave)
One Lunatic Catoblepas. This boss can inflict stone on you but one you've killed it, its gone. Apart from that, not much threat.
Wave 2 (Boss Wave)
One Lunatic Chimera Golem. This boss is a tanky one. It changes its elemental weakness and the debuffs it inflicts based on its form. Goat is weak to Fire and inflicts DEF Down, Lion is weak to Wind and inflicts SPD Down, Dragon is weak to Holy and does an AoE BRV+HP Attack than can kill you. You can summon here as you cannot summon on the last wave. Keep your current BRV health and keep the enemy broken and you should be fine.
Wave 3 (Boss Wave)
One Lunatic Astaroth. Get broken and it will follow-up with Drain that can kill. Thus, don't get broken and you should be be able to kill it as its squishy.
Wave 4 (Boss Wave)
One Lunatic Cray Claw. This enemy is Thunder weak and absorbs Water. It can also increase BRV with its group attack and one shot your character. Keep it broken and the threat will be to a minimum.
Wave 5 (Final Boss Wave)
One Lunatic Ultima, the High Seraph. Ultima absorbs Holy. First of all, Ultima prohibits summoning so as mentioned earlier, best to summon on Wave 2. Note that its Holyja attack removes your generic buffs. It also has Holy Crush which is a ST BRV+HP Attack. Its most powerful attack is Eschaton which is a guaranteed hit, BRV Gain + AoE BRV + AoE HP Attack. Not only that but it uses Pranormal Field which inflicts one status effect on you - it cycles from Poison, to Turn Rate Down, to Paralyze. Just keep youself healthy with HP, don't get broken and dish out damage. When Ultima is at 50% HP, it will use Renew and restore its HP back to 100% but this only happens once. Debuff evasion helps to prevent being paralyzed. Continue doing the basics and you should be able to kill Ultima.
Most Used Units. Cloud is the most used unit for this tier. With his amazing on-demand launch and DPT, even if the bosses are immune to his paralysis, he can aid your team well. Yshtola is another mvp with her amazing batteries and delay. Garland with his DPT and delay. Selphie with her great auras and 70% debuff evasion. Noel and Machina with their ST DPT. Sherlotta, Locke and Cait Sith with their healing capabilities and support. Special mention is Tifa with her amazing ST DPT and launch.
EX Only Units. Selphie and Lenna will greatly help with the debuff immunity with their base EX. Noel with his DPT and delays. Sherlotta with her usual amazing burst and heals.
Summons Used. Note that the last wave does not allow you to summon so you want to use it on earlier waves. The best wave to use it on the Chimera on the second wave as it is the tanky. Once the Chimera has a blue aura, it means it is weak to Fire - summon Ifrit away and burst it down.
Top Unit. Cloud is the top unit for this tier. Since he has limited skills, you'll want to reserve them on buff up-keeping. His HP+ is also decent thanks to his BRV regen. Due to the tight score, his launches help greatly. Try to aim launching with all three units with his 4 Finishing Touch skills. He pairs well in this tier with other ST damage dealers like Machina, Garland and Locke. You'll also want to have aura/support/battery beside them like Rem, Selphie and Yshtola and pump their damage up.