All values come from the item tooltips on BianKO's own site. The site has 13 tooltips with the Shield type, and all of them are below except the low-plus Small Shields.

Shield stats

BianKO shields by defense
ShieldDefenseBonus statsRequiresSource
Dread Shield 245 — STR 90 Silvery Gem 0.005%; Red Gem 0.002%; Blue and Yellow Gem 0.001%
Syphioric 195 20 AP, MP 100, STR +2 STR 90, Health 90 Ornament 0.27%; Random Item Exchange Gem 0.164%; Fragment of Avarice 0.056%
Shield of ‹selfname›(+1) 195 Health, STR, DEX, INT +1; 20 defense vs sword, club, axe, spear Level 70, STR 94 Random Item Exchange Gem 0.492%
Defender of the Lord 185 HP 10, MP 10; 5 defense vs dagger and arrow; Repel Physical Attack 5 STR 90 Black Treasure Chest 2.381%; Random Item Exchange Gem 0.328%; Dark Fragment of Lust 0.095%
Plate Shield(+1) 144 — STR 114 Group drop of 39 mob records
Round Kite Shield(+5) 135 40 defense vs dagger STR 108 [Shackled Lord] Fluwiton (9512) group drop
Large Kite Shield(+1) 118 — STR 100 Same mobs as Plate Shield(+1)
Kite Shield(+1) 92 — STR 86 Same mobs as Plate Shield(+1)
Scorpion Shield 88 HP 100, MP 100; flame and poison resistance 30; glacier, lightning, magic, curse 15 STR 51 Main drop of Lesath (908), Shaula (907), Ultima (6501); 34 mob records
Small Shield(+7) 71 Repel Physical Attack 22 STR 69 16 mob records between level 20 and 47 (Werewolf, Lycan, Dire Wolf, Shadow Seeker)

Dread Shield has 50 more defense than Syphioric, but Syphioric adds 100 MP and 20 AP. Defender of the Lord has less defense but has the highest listed rate of any unique shield: 2.381% in Black Treasure Chest. Plate Shield and Large Kite Shield are middle Class, Kite Shield is low Class, and Round Kite Shield(+5) is a Rare item.

Where the shield boxes come from

  • Colored Gems (Dread Shield): Silvery Gem is a main drop of Devabird (8106), Lich King (8100), Minotaur (8103) and Bone Dragon (8104). Blue and Yellow Gem are in the group drop of Devabird and Pride (5801). No mob page drops Red Gem, and Black and Green Gem show Dread Shield at 0%.
  • Fragments (Syphioric): group drop of Wrath (6001, level 88).
  • Random Item Exchange Gem (Syphioric, Shield of ‹selfname›, Defender of the Lord): main drop of Pride (5801, level 83).
  • Ornaments (Syphioric, Defender of the Lord): Snowman (2702, level 70).
  • Black Treasure Chest and Dark Fragment of Lust (Defender of the Lord): no mob page lists them.

The Power Up Store sells a Shield of ‹selfname› Converter for 999 KC. The site doesn't explain what it converts.

Scorpion Shield: low defense, high resistances

Scorpion Shield sits near the bottom at 88 defense, but it's the only shield that adds 100 HP, 100 MP and six resistances, and it only needs STR 51. It's a main drop of Lesath and Shaula, and it's also in the group drop of level 83 mobs like Medusa, Ice Golem, Blue Phoenix and Hades and of bosses such as Ultima (6551), War Monument and TREE BOSS.

FAQ

Does Dread Shield drop from mobs?
No. No mob page lists it; it's only in the Black, Blue, Green, Red, Yellow and Silvery Gem lists, highest in Silvery Gem at 0.005%.
Can you upgrade shields?
Plate Shield(+1), Large Kite Shield(+1) and Kite Shield(+1) are plussed items, and their tooltips say middle or low Class. The site has no upgrade info for the unique shields (Dread Shield, Syphioric, Defender of the Lord).
Where does Round Kite Shield(+5) drop?
From the group drop of [Shackled Lord] Fluwiton (9512), a level 90 mob with 847,452 HP whose main drop is Gold Bar and Silver Bar.
Scorpion Shield or Dread Shield?
For flat defense, Dread Shield (245 vs 88). Scorpion Shield brings HP, MP and resistances instead, and it actually drops from mobs.

Related guides