Foh is no way invincible. You can be shot or stabbed or blown up whilst implementing it. Even if you do get to implement it the victim just has to jump, go up stairs, down stairs or nip backwards and it is useless. Even more annoying is when there are a group of opponents and you jump in to foh them and you hit a rock, ledge, small flower etc and again it is rendered useless. I also turned my Titan defensive today and both my ward of dawns were blown apart instantly and I ended up dead both times. Titans are so under Op it is ridiculous.