This card is treated as a Normal Monster while face-up on the field or in the Graveyard. While this card is face-up on the field, you can Normal Summon it to have it become an Effect Monster with this effect.● Once per turn: You can Special Summon 1 Zombie-Type monster from your hand or from either player's Graveyard. When this card leaves the field, destroy all Zombie-Type monsters Special Summoned by this card's effect.
Goblin Zombie works very well with Il Blud. When it's sent from the field to the Graveyard, you can search Il Blud from your deck and add it to your hand since Il Blud has less than 1200 defense. Once you summon Il Blud, you can use its effect to Special Summon Goblin Zombie from the Graveyard. When Il Blud leaves the field, the special summoned Goblin Zombie will be sent to the Graveyard, which again will trigger its effect.
By using Gozuki's effect, you can send Zombie-Type monsters from your Deck to your Graveyard. You can Special Summon Il Blud from your hand by banishing a Zombie-Type monster in the Graveyard when Gozuki gets destroyed. Il Blud now can Special Summon those Zombie-Type monsters that Gozuki sent to the Graveyard.
Bone Crusher has a great synergy with Il Blud. It can destroy your opponent's back row cards when it's special summoned by Il Blud from the Graveyard. This card will be destroyed during the End Phase when it is special summoned. Then on your next turn, Il Blud can special summon it again from the Graveyard and Bone Crusher can again use its effect. Basically, you can destroy 1 card in your opponent's back row every turn by doing this process.
You can pair these cards on Il Blud since they're also Zombie/Gemini-Type monsters. Heavy Knight of the Flame has an effect that could banish a special summoned monster by attacking it. While Skelesaurus can special summon the monsters that it destroyed in battle.
The problem with Gemini monsters is that you need to normal summon them again to gain their effects, which is waste of turn since you can summon another monster instead. By using these cards, you can have their effects without normal summoning them again.
Destroys Monster Cards / Destroys Special Summoned monsters
Special Summons from your hand / Special Summons from your Graveyard / Special Summons from your opponent's Graveyard
Treated as a Normal Monster
This card would be far more usable if we get Zombie Master.
Zombie Master is a good target for this card's effect, allowing Zombies to swarm the field quickly.
Zombie Master itself cannot special summon itself into the field and thus needs assistance, but most Zombies special summon themselves instead of other Zombies. Il Blud and Zombie Master are one of extremely few that special summon other Zombies.
I was thinking, since the new skill Posthumous Army affects both players' Graveyards, could you use it to take the opponent's monsters from their Graveyeard with Il Blud's effect? Since Il Blud can take Zombie monsters in both Graveyards, it would be possible right?