maybe on offense, probably not on defense. depends on who else you have in your collection.

mk is a decent choice for a go second team, due to his ridiculous base stats making him super tanky. the problem is that he's incredibly slow, only targets one champion at a time, and doesn't have anything like reduce max hp or block revive that ensures he can bring the fight to a close. on offense you can pick your targets and focus on taking down your enemies one champion at a time but on defense, without you controlling him manually, he's far more likely to just ineffectively target your opponents dps over and over and over.

Ok on offence where you can pick the teams to use him, not a good choice on defence where he can be easily countered.

Even on offense, I think I'd probably pick just about anyone else over him. All he does is damage, and while his damage is certainly not bad, rarely is there room for someone to only do single-target damage, with no max-hp reduction or block revive or anything like that.

thanks all