Shapesharer

If Shapesharer itself becomes a copy of another creature, it loses both changeling and its activated ability (unless it’s copying another creature with changeling and/or another Shapesharer, of course).

Effects that have already applied to the targeted Shapeshifter will continue to apply to it. For example, if Giant Growth had given it +3/+3 earlier in the turn, then this ability makes it a copy of Grizzly Bears, it will be a 5/5 Grizzly Bears.

If the targeted Shapeshifter copies a creature that’s copying a creature, it will become whatever the chosen creature is copying.

This ability can cause a creature to become a copy of itself. This will usually have no visible effect.