Well if every Sentinel acted everytime it’s effect was activated, it’d be a different. Can’t attack twice with Skull prophet as you’d hit 0. Zendo Mizuchi decks. Bound tomentor would be the new MCO, Rakushi would be so anti swarm that it would be run. Only vanar neutral sentinels would work regularly?
So Sentinels could be much more anti and effective and fun, but since they aren’t you only use the useful ones and MCO and Basalisk aren’t answer or die. Don’t play spells if that’s what you suspect, unless it’s an answer. MCO should get two spells at best. Basalisk as an immediate 5/5 can be troublesome, but not death. Given I usually expect Spell sentinels, they aren’t that bad and rarely have an opportunity to snowball.
Pro tip: use obtuse removal like sky burial so you can Vaath Wink or Argeon Smile if you prefer Decimate.