This missionaries should just stop trying because they're not converting me anytime soon. In their basest element, this card is a 2/3 for 5 mana, and that just sucks. I mean, it's got no evasion, no protection, no abilities; it's just there. Granted it does have an ETB trigger of gaining life, but does that warrant a 2 mana cost increase (using Alaborn Trooper as a base)? Not really, since Healing Salve, which is more versatile and faster, only costs 1 mana. This card has no redeeming qualities since it's way too expensive for what it does.
Pros: Gains you 3 life when it enters the battlefield
Cons: Massively overcosted, no evasion, essentially vanilla