extremely fun rules interaction: the tarrasque's first ability is a static ability that, in effect, constantly checks to see whether the permanent has the quality "was cast". unless I'm very wrong (and I rarely am about rules in mtg) if you renimate or otherwise cheat the tarrasque into play, and then mutate something else on top of it (the on top part is important), the resulting creature will have this ability and the quality "was cast" and will therefore have haste and ward 10, because mutate is an alternate casting cost, not an activated ability. this isn't generally very useful as you'd usually just rather have the 10/10 but it is neat
Fun fact: it doesnt have to be on top! Just so long as it's part of a mutate stack, the tarrasque was considered cast and as such has Ward 10 and Haste!
For a source here is the answer from the current rules manager
