If a player becomes Ragnaros (that has a 8HP limit) by using Majordomo Executus' deathrattle, he can subsequently play Alexstrasza to increase his HP to 15.
What happens if, after suffering damage, the player summons Reno Jackson, triggering his battlecry? Is 15 the new permanent maximum, or is 8 still considered "full health" for Ragnaros?