If abilities could destroy terrain realistically, then which ability would cause the most damage?

UNSTOPABBLE onslaught

Asols q hes literally creating a star and gravity would suck up the entirety of the rift

and read their lore

karthus ult

AS's Passive is to have 3 baby stars flying around, that would cause some damage. In the way of not cosmic star crafters, GP's ult is a huge barrage of cannonballs, which have been known to destroy small mountains.

reksais tunnel.

New Galio ult, Ziggs ult.