the ability changeling was designed from a flavor perspective, not a working mechanic perspective. HOWEVER, you can take one look at a creature with changeling and go. oh it has all creature types. also, when you have no room for reminder text, changeling makes "this creature is all creature types at all times" fit alot easier into the box.
Solid Illusion1UU
creature - illusion
whenever another illusion permanent is put into a graveyard from the battlefield, it's controller may put a creature token into play that's a copy of that creature. it gains "whenever this creature becomes the target of a spell or ability, exile it."
2/3
Lord of Ressurection1BBB
creature - zombie wizard landfall - whenever a land enters the battlefield under your control, you may cast target zombie card in your graveyard without paying the casting cost.
3/3
Rage Phoenix3RR
creature - phoenix
flying
phoenix creaturs you control get +2/+2.
whenever a phoenix is put into your graveyard from the battlefield, you may pay the card's converted casting cost. if you do, return that card from your graveyard to the battlefield at the beginning of your next upkeep.
3/3
Seedborn Sage3GG
creature - spirit
whenever a land you controls becomes untapped, you may add one mana of any color to your mana pool. mana produced this way doesnt empty until the beginning of your end step.
2/4
Chains of Glamer2WWW
enchantment
creatures that are enchanted cannot attack or block. activated abilities of creatures that are enchanted cannot be played.
Resource Theft1BB
enchantment
whenever a land card is put into an opponent's graveyard from the battlefield, you may pay 2B. if you do, return that land to the battlefield under your control.
enchantment
whenever a source you control would deal damage to you, prevent it. you gain life equal to the damage prevented.
official rules advisor. it gets me there.
enchantment
nonlegendary creatures you control have the same name as this card.
official rules advisor. it gets me there.
enchantment
whenever a card you own is exiled from anywhere, put it into your hand at the beginning of the next end step.
official rules advisor. it gets me there.
instant
copy target activated or triggered ability, you may choose new targets for the copy
madness U
official rules advisor. it gets me there.
Solid Illusion 1UU
creature - illusion
whenever another illusion permanent is put into a graveyard from the battlefield, it's controller may put a creature token into play that's a copy of that creature. it gains "whenever this creature becomes the target of a spell or ability, exile it."
2/3
official rules advisor. it gets me there.
enchantment
whenever you sacrifice a creature, gain 3 life.
official rules advisor. it gets me there.
creature - zombie wizard
landfall - whenever a land enters the battlefield under your control, you may cast target zombie card in your graveyard without paying the casting cost.
3/3
official rules advisor. it gets me there.
creature - phoenix
flying
phoenix creaturs you control get +2/+2.
whenever a phoenix is put into your graveyard from the battlefield, you may pay the card's converted casting cost. if you do, return that card from your graveyard to the battlefield at the beginning of your next upkeep.
3/3
official rules advisor. it gets me there.
shared resources 1G
enchantment
lands you control gain all activated abilities and land types of other lands you control
infinite mana? yes please.
official rules advisor. it gets me there.
creature - spirit
whenever a land you controls becomes untapped, you may add one mana of any color to your mana pool. mana produced this way doesnt empty until the beginning of your end step.
2/4
official rules advisor. it gets me there.
artifact
whenever you would draw a card, you may reveal that card, then choose to cast it.
official rules advisor. it gets me there.
Chains of Glamer 2WWW
enchantment
creatures that are enchanted cannot attack or block. activated abilities of creatures that are enchanted cannot be played.
official rules advisor. it gets me there.
Power From Exhaustion 1RR
enchantment
tapped creatures that aren't attacking get +2/+0.
official rules advisor. it gets me there.
creature - elemental shaman
whenever an activated ability is played, you may have ~ copy that ability.
3/2
official rules advisor. it gets me there.
enchantment
whenever a land card is put into an opponent's graveyard from the battlefield, you may pay 2B. if you do, return that land to the battlefield under your control.
official rules advisor. it gets me there.