[Gameplay] Lissandra not invulnerable nor untargetable while in self-cast Frozen Tomb.

While playing as Lissandra on 3/11/2016, I self cast Frozen Tomb a total of three a total of three times. In all three cases, I continued to take damage during the 2.5 seconds during with I should be untargetable and invulnerable. The first two times I died within a second or two after casting ult. I was unable to determine if I was receiving the healing or not as in each case I continued to take damage greater than the healing would provide if it was present during the Frozen Tomb duration.