Rules says:
If a card loses the changeling ability, it will still have all creature types. It just won't have changeling.
I dont understand that interaction. Its the changeling ability that gives all creature types, right ? else its a shapeshifter. so why does loosing the changeling ability not result in losing all creature types ?
Changeling functions more as an abbrevation than an actual ability. Since it is impossible to write all the existing (and not yet existing) creature types in the usual spot on the card, the keyword "changeling" helps. That's the way I understand it, at least. Shapeshifter is written down because something has to be, and shapeshifter is most appropriate of the bunch.
Changeling's effect is a type-changing effect, which applies in an earlier layer (C.R. 613.1d, layer 4; C.R. 702.72a) than effects that remove abilities (such as found in Kasmina's Transmutation) (C.R. 613.1f, layer 6). Because of this, the effect of changeling on the creature enchanted by Kasmina's Transmutation (if it otherwise has changeling) will still give the creature all creature types even though that creature loses changeling due to Kasmina's Transmutation. See also this thread.
When multiple effects combine to modify an object, it may be difficult to establish exactly which effect does what. Rule 613 has been devised to settle such complex and/or contradictory interactions. Specifically, rule 613 states that some kinds of modifying effects MUST be applied to the affected objects BEFORE some other kinds.
As has been said, an effect that GRANTS a creature some SUBTYPEs (such as Changeling does) must be applied BEFORE an effect that would remove an ability (such as Transmutation does to Changeling). Removal of Changeling therefore happens TOO LATE: the subtypes have already been granted to the creature.
613.1. The values of an object’s characteristics are determined by starting with the actual object. (…) Then all applicable continuous effects are applied in a series of layers in the following order:
(…)
613.1d Layer 4: Type-changing effects are applied. These include effects that change an object’s card type, subtype, and/or supertype.
(…)
613.1f Layer 6: Ability-adding effects, ability-removing effects, and effects that say an object can’t have an ability are applied.
why does it not lose all creature types ?
Rules says:
If a card loses the changeling ability, it will still have all creature types. It just won't have changeling.
I dont understand that interaction. Its the changeling ability that gives all creature types, right ? else its a shapeshifter. so why does loosing the changeling ability not result in losing all creature types ?
As has been said, an effect that GRANTS a creature some SUBTYPEs (such as Changeling does) must be applied BEFORE an effect that would remove an ability (such as Transmutation does to Changeling). Removal of Changeling therefore happens TOO LATE: the subtypes have already been granted to the creature.
(…)
613.1d Layer 4: Type-changing effects are applied. These include effects that change an object’s card type, subtype, and/or supertype.
(…)
613.1f Layer 6: Ability-adding effects, ability-removing effects, and effects that say an object can’t have an ability are applied.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules