I would recommend it, rune stones provide some definitely useful stat boosts

Blazing bison but would it be better to spend on magatamas?

nahh its better to spend on runestone

You can get magatamas as rewards for ninja exam and other daily events, but you can only get runestones from cave keys or spending the coupons.

Raw stats from magatamas are also less useful than the boots runestones can provide imo.

Yes it is especially with the key consumption event goin on now.

NO NO NO save them for the next lucky board event, the key consumption is NOT worth it, in lucky board you actually get rare ninja fragments and other free stuff and by spending like 500-1000 coupons you can actually get lots of seal scrolls too usually enough for a 10x pull.

if you really want you can save like 990 coupons and buy a ''key pack'' that has 88 keys and usually it comes with a 20-30% discount so you can get it for cheaper, wait for that event.

trust me I had over 1k coupons and 1200 ingots and I went for sage jiraiya and jigukudo frags (I needed 40 frags of each) instead of keys.