If a shaman has 10.000hp you can use water elemental and trinket.
Shatter combo that does 4500dmg and a fire blast for 1000dmg.
Then there's only 4500hp left. When they are trying to heal just use counterspell and then you can blink, frost nova, ice lance and cone of cold. If they use grounding totem do a ice lance on it and then nuke.