
you can still fusion summon, the fusion just goes in defense position - level limit, not vanity's! fusions with battle effects will be hurt a lot, but others like kimeterasu and the metarions can play through it just fine

i think your misunderstanding... cause your not gonna fuse and risk getting otked. cause thats the problem. its the litteral reason it s otked read the fusions

but not fusing won't help you not get otked at all! if you can contest the yamiterasu (and several fusion monsters can), you will.
and if they can field kimeterasu, then they have kimeluna, who can change everything on your board to defense position to wipe it away anyway. kimeterasu is the much better fusion of the two, yamiterasu is actually relatively niche. either way, the point of the limit is really just to stop you from playing 3 yamiruler in main deck

ive seen so many confusion about the limit 3 here: its cause its an otk play. basicly your going to otk next turn if you draw 4 cards and only way to stop it is negate attack and yea lets be honest here your not garanteed to draw it