Infestation

Evoke represents two abilities: a static ability that functions in any zone from which the card with evoke can be cast and a triggered ability that functions on the battlefield. “Evoke [cost]” means “You may cast this card by paying [cost] rather than paying its mana cost” and “When this permanent enters, if its evoke cost was paid, its controller sacrifices it.” Casting a spell for its evoke cost follows the rules for paying alternative costs in rules 601.2b and 601.2f–h.

Wither is a static ability. Damage dealt to a creature by a source with wither isn’t marked on that creature. Rather, it causes that source’s controller to put that many -1/-1 counters on that creature. See rule 120.3.

If an object changes zones before an effect causes it to deal damage, its last known information is used to determine whether it had wither.

The wither rules function no matter what zone an object with wither deals damage from.

Multiple instances of wither on the same object are redundant.