Minecraft wiki entry for Death_messages, associated text: <player> was slain by <player/mob>
Appears when the player is hurt by a player or mob and killed.
This death message is actually two different death messages: <player> was slain by <mob> and <player> was slain by <player>.
This means they can be customized completely independently of each other using resource packs.
<player> was slain by <player> also appears when a parrot is fed a cookie.
If the parrot was named, the message will appear in the game's log. If it was tamed, the message will be sent to its owner.
<player> was slain by <mob> also appears when the player is killed by a shulker using a shulker bullet, or a llama using its llama spit.
If the player was killed by a shulker bullet or llama spit summoned with /summon, the death message is <player> was slain by Shulker Bullet/Llama Spit.
<player> was slain by <player/mob> using <item>
Appears when the player is hurt by a player or mob holding a renamed item and killed.
This death message is actually two different death messages: <player> was slain by <mob> using <item> and <player> was slain by <player> using <item>.
This means they can be customized completely independently of each other using resource packs.
<player> was slain by <player> using <item> also appears when a parrot is fed a cookie by a player holding a named item in their main hand.
<player> was slain by <mob> using <item> also appears when the player is killed by a shulker holding a renamed item using a shulker bullet, or a llama holding a renamed item using its llama spit.
<player> was fireballed by <player/mob>
Appears when the player is killed by a fireball shot by a player or mob.
When the player is killed by a fireball shot from a dispenser or summoned with /summon, the death message is <player> burned to death.
<player> was fireballed by <player/mob> using <item>
Appears when the player is killed by a fireball shot by a player or mob that was holding a renamed item during the player's death.
<player> was stung to death
Appears when the player is killed by a bee (not from its poison).
death.attack.sting.item
Appears when the player is killed by a bee that was holding a renamed item during the player's death.
This death message is untranslated due to MC-186851.
<player> was shot by a skull from <player/mob>
Appears when the player is killed by a wither skull shot by a player or mob (only possible with the Wither).
When the player is killed by a wither skull summoned with /summon, the death message is <player> was killed by magic.
death.attack.witherSkull.item
Appears when the player is killed by a wither skull shot by a player or mob that is holding a renamed item during the player's death.
This death message is untranslated due to MC-186148.