League-of-legends – Are item passives implicitly passed on into higher tier items

There's a thread about this on the official forums now. Here's what they say:

• Zyra gains 1 hp/5 seconds when she is near a friendly Leona. Photosynthesis!
• Yorick's ghouls will only target plants if they're in range instead of targeting champions (different from their minion targeting behavior). Plants vs Zombies!
• Maokai gains 1 movespeed when he is near Zyra.

See also: this Reddit thread.

Although the links provided in the question answer it fully, just so we have an accurate answer on the site.

1. Zilean's Chrono Shift ability. Caveats being:
   • Chrono Shift will not activate if the holder is killed by the Nexus Obelisk.
   • Chrono Shift will always take precedence over other revival abilities, like Guardian Angel and Rebirth.
2. Guardian Angel item. Caveats being:
   • The passive does not activate when killed by the Nexus Obelisk.
   • Its passive will always activate before Rebirth, but after the Chrono Shift buff if the owner has it.
3. 3a Aniva's Rebirth ability. Caveats being:
   • If Anivia is affected by Chrono Shift, Omen of Death and/or Guardian Angel, Chrono Shift will activate first, Guardian Angel second, and Rebirth will be third. Omen of Death will have last priority, granting Anivia the potential to survive up to four "deaths".
4. 3b Zac's Cell Division passive.
   • Each bloblet is 12% of Zac's max health, has 50% of his armor/mr, and take 33% reduced ae damage.
   • Based on the bloblet's life on joining is the amount Zac will be at.(eg. if ones dead, another is at 50% and the other 2 are at 100%, Zac will revive at 30%).
   • Bloblet's are treated as minions in terms of abilities like consume and smite.
5. 3c Aatrox's Blood Well passive.
   • The amount of health returned is equal to the amount in the blood well + (10.5 + 15.75*lvl).
   • Affected by passive of Spirit Visage.
6. Yorick's Omen of Death ability. Caveats being:
   • Omen of Death has the lowest priority in terms of revival because it does not resurrect the champion, only revives them temporarily. This means that if an ally were to die while under the effects of Zilean's Chrono Shift or Guardian Angel as well as Omen of Death, the champion would be affected by the one that prevents death.
   • In Dominion, during the reincarnation of Omen of Death, Yorick or the champion brought back can not capture a point or stabilize a point to stop it from firing at an ally.
   • During the reincarnation of Omen of Death, you cannot use any summoner spells.

Other notes: Although not considered a revive ability, Mordekaiser's Children of the Grave ability has lowest priority. In most cases, the debuff is cleared by the original death if the person is revived. When Aniva's ghost is revived by this ability, it may enter the egg state, but this will not affect the actual Aniva's ability cooldown.